I know that in 3.x (including Pathfinder) it's common to talk about different tiers of classes in terms of power and versatility. Does this also apply to Starfinder, and if so, what are they? I rarely play with serious optimizers, but it would be nice to know if there are "trap" options that will leave one character feeling useless most of the time. (Yes, I do have the book but historically I'm a sucker for flavor and don't realize I've made an underpowered character until too late, and with a new game I wouldn't want that to happen to me, or to one of my players if I'm GMing.)
The answer is almost-certainly yes. There is no such thing as a perfectly-balanced game, and any game with imbalances can have options categorized into tiers.
Whether those tiers look anything like those in Pathfinder, how many tiers there are, how wide each is, and what class falls in each tier, those questions are basically impossible to answer at this point. It’s just too soon in Starfinder’s lifetime to know these things; we can guess based on past knowledge, but inevitably there will be subtle differences with some significant consequences, and these are not going to be discovered and recognized for some time. Ultimately, Stack Exchange is a good place to compile and record the findings of the optimization community, but it is a poor place to explore optimization possibilities.
The earliest opinions that I have seen are complaints about the envoy and solarian classes, for what that’s worth. I have also seen folks express some uncertainty about the validity of those complaints, and that there may be more to those classes than people think (though the weakness of the disagreement suggests to me that there is at least something amiss there).
Starfinder is explicitly far more focused on balance from the ground up than pathfinder ever was. While certain gaps are inevitable, it's going to be much closer than other systems, and not what I'd call "tiered". They crunched the numbers a lot more in the development of Starfinder.
That being said, if you're talking combat damage, Starfinder did not change the Pathfinder truism of two-handed melee being king. To steal a graph from elsewhere on the site: That is just raw weapon damage, not factoring in any special effects, but it does illustrate the point.
The issue with "linear fighters, quadratic wizards" found in 3.x and Pathfinder has been at least mitigated on a couple levels, reducing the tier-boosting that full casters used to get. A lot of utility that used to belong to full casters now belongs to technological items, and low-level spells don't scale up in power with level. So if you want to be dealing higher level damage, you need to be burning higher level spell slots.
In short, no, tiering isn't gone, but they're a bit narrower. Some classes take a bit to catch up (like Operative lagging somewhat before level 7), but while there may be some poor builds, there's not really any bad classes anymore.