OK, we started a new campaign yesterday and I really want to take quality feedback from my players. When I ask, "How was it? Do you like it?", I generally get some vague answers like "It was good, I like it" in response.
So, how can I take better feedback from my players? What can I ask and how can I ask?
Ask them about their experience. People are hesitant to criticize both friends and authority figures (and as a GM you fit into both categories). The answer to "how did I do" is always "fine." The answer to "did you have fun during the session, what did you enjoy or not like" is always much more evocative (and frankly casting it as about them indicates that you care about their experience, not just "making yourself better"). Similarly, ask proactive and not just reactive questions like "what would you like to see more of/less of in the campaign?" That is framed as campaign planning and engages forward thinking, not as retroactive fault finding, which is more helpful to you and less threatening to them (except for the very negative folks who love to criticize, in which case you need to divert them from every picky little thing they didn't like to "what should we be doing instead" anyway).
Surveys. A way to avoid squeaky wheel syndrome (one or two people who are willing to speak up get their stuff in, but others who are quite and may have very different experiences don't). Make sure and ask for degree and not just yes/no, just like any real survey you ever take - "How much do you enjoy the romance subplots, fill in the appropriate bubble - o Greatly o Somewhat o Indifferent o Not much o Dislike strongly." This will get you everyone's opinion and you'll know how strong it is - in casual conversation it can be hard to determine whether someone's more "well I don't really get into those but don't mind them" or "I really hate those and wish they'd stop."
Take feedback well. Inevitably when a GM asks for feedback, someone will say "I didn't like it" and they'll get upset, and then everyone learns not to tell them what they really think. You will have to be thick skinned if you really want feedback. And you'll have to act on the feedback, if people tell you something a couple times and you don't change, they will assume you're not listening. And it's hard to balance that because any good campaign isn't formed by focus group (sorry indie-game narrativists), it requires a good driving vision. You can help yourself by framing questions not directly about yourself, but indirectly about "things in the game" and "techniques I used."
A general rule of thumb is that people will answer specific questions with more detail than open ended questions or questions that imply potential for personal conflict (i.e. "how did I do" is unlikely to get honest answers except from your really closest friend - but instead something like "did you like the balance between roll playing and role playing?" or "what could we add to the table to make combat go more smoothly" etc.
i.e. ask specific questions that solicit input (which you can act upon)
Then after you act upon suggestions - especially relatively minor ones, it becomes easier to get answers (in the future) to questions about bigger items (i.e. after you fix little things about the scheduling of the game or the house rules or the layout of the table for combats then you can more likely get input about bigger items like game style, your DMing style, whether you should stop trying to do multiple voices etc.)
Another suggestion - though this depends on the relationship(s) you have with players is to set aside time to talk with each player outside of the game session about their feedback. At the end of the night as people are packing up to leave may not be the best time to get detailed feedback - but grabbing coffee later in the week, chatting over Skype or even just some one-to-one emails or a quick phone call could get you far more detailed feedback.
You may also want to start the next session with a short (emphasis on short) group discussion about what is working/isn't working and quickly make adjustments that might help with the flow of the game - i.e. fix physical setup, talk about the time of the game, breaks, whatever.
With any game it is also important to keep in mind the expectations of the players and make sure that they match with each other and with your expectations as the DM.
In my experience, the input you want on your sessions is almost identical to the suggestion I made over on the What can I learn from playtesters? question... [excerpted here:]
I like to watch body-language and facial expressions for signs of boredom, confusion, distraction, surprise, delight, and especially for game events that cause a radical shift in a players emotional state (either direction).
Note that nowhere do you ask "how did I do?"
Maybe give it a little time before digging for detailed feedback - if the campaign is new (and especially if the game group is new), people need a little time to find their voices.
With that in mind, an open discussion about everybody's goals and enthusiasms can go a long way. If you find out why they are playing, that will help you give them what they want. If one guy is all about the fighting, you can feel more confident in your GMing if you take a little time to create interesting and challenging combat situations he'll enjoy. Then, later, you can ask if you are giving them what they said they want, and also if what they want has changed over time. That's much easier to respond to.
You might have better luck one-on-one as well. Try inviting somebody out for coffee to talk over the game.
I recently gave my players a survey on how they felt about the game. When I was asking for verbal feedback they kept giving one word answers, so I had to try something new.
Anyway, I listed a bunch of things from the game and asked the players to cross out those they disliked and circle those that they liked. Kinda like StackExchange's upvote/downvote system.
Here's the survey: https://docs.google.com/document/pub?id=1qLAvhgbA7uyK2iTF7jYvYXIIWP-zPAiu5Nt6vEW4dYg No, I don't expect the names of plots and NPCs to mean anything to anyone, but you get the idea. (Although I will point out that "fishrape" is what the players have elected to call the Aboleth plot I'm using, that's not the name of the plot as I've conceived of it.)
This was more interesting than the other forms I've encountered because it was so specific. In my LARPing days I answered a lot of questions about how I feel about romance in games. Or if I feel I need to win. Or if I mind being a jerk. But without context I can't always say how I feel about those things. So instead I gave the players the context and let the players vote to place themselves there or not.
One way is to offer moderate in-game rewards for comprehensive journal entries about the sessions. Hand off a bit of extra XP to those willing to take their time and write some kind of a decent summary about what happened, either from an in or an out of character point of view.
Handle this with care, though: don't reward writing style or word count, for not everyone's born a writer (and you don't want the group's writer to advance way ahead of the others.) Set a minimum entry level ("at least five proper paragraphs", for example) that qualifies a journal entry for the reward... and thank/honor each contributor equally.
Once (and if) the journals start coming in, you may get back to their writers with a few specific questions.
Edit: An additional tip: You may want to start an invite-only, multiple-author blog (at blogspot.com, for exmaple - I think it can be done over there), and get your players not only to post journals there but to comment on others' journals as well. This has the additional advantage that you can post resources (images, descriptions, downtime summaries etc) as well, asking for player feedback (and perhaps declaring, in some cases, that the story won't roll on until a number of players haven't left comments on a post.)
As you already pointed out, "How did I do" gets vague answers. I just finished an adventure, and got pretty good feedback with the following 4 questions:
You may get 1 word answers, or you may get pages of response per question. Keep a copy of the first 3 questions, and if something comes up in-game, jot down a quick note to yourself. I would also jot down any rule I couldn't find in about 2 minutes, and then hand-waved. I'd suggest you only ask the players once per adventure/Chapter. Otherwise it will start to annoy the players and the will give you "it's fine" dodge/cover.
One way that serves a dual purpose is to get one player per session, at the beginning of the session, to do a summary of last session. The things they focus on and the way they tell it should give you an idea of what they did and didn't enjoy and what they focused on mentally.
And, of course, it reminds everyone what happened last session.
I would like to add as an addendum to previous posts involving surveys:
While you want to give the players more than just simple "yes/no" questions on them, remember that your players have lives (work, family, friends, school) and try to keep it as concise as you can. If you keep your survey manageable and try to get as much as you can to each question, they're much more likely to answer it, in my experience.
I think the World of Darkness rule for end-of-chapter experience is excellent into indirectly getting a feedback from the players.
At the end of each chapter, each player gets:
while they all provide insight, especially if you discuss them with the players, the "learning curve" one helps them a lot to focus on what actually happened, what they did, why, etc. While they tell you about that, you can understand the game from their perspective, and that's a feedback way better than a plain "did you have fun?".
I usually approach this is a round about manner I guess. I have all the player in hat submit who they thought role played the best, and if and situation they would like to take offline, or effected them in a specific way. We tally votes award xp. I also tend to encouraging players to develop a large back story and submit it to me so I can make the campaign more fun for them, and add story the would like to see develop. In essence your getting your feedback, encouraging role playing, and not really having to straight out ask.
