Some of the feats in D&D 5e are seemingly less useful or otherwise not always as reliable relative to the other feats, although they are very flavorful. Keen Mind is one such feat, granting your character a 30-day eidetic memory, master navigator, and time keeper.
However, there can be workarounds for the last two benefits (benevolent DM, hand waving, finding NPCs who know the area, etc), and the first benefit does not seem to have an everyday usefulness to shortlist this feat for a wizard -- not over War Caster, Resilient(Con), Alert, or Tough, for example.
At best, people seem to think it's just a way to make the DM rehash their old hints if you missed them the first time.
Here is the text for Keen Mind:
You have a mind that can track time, direction, and detail with uncanny precision. You gain the following benefits.
- Increase your Intelligence score by 1, to a maximum of 20.
- You always know which way is north.
- You always know the number of hours left before the next sunrise or sunset.
- You can accurately recall anything you have seen or heard within the past month.
If you're a wizard, you will be reading your spellbook everyday. It is within the bounds of the feat to say you recall absolutely every glyph, symbol, and diagram of your spellbook, down to the ink stains and page number of each word of each spell.
One cool way to make use of Keen Mind is to make the spellbook obsolete -- within the DM's approvals/restrictions.
Here are things a wizard can do because of their spellbook:
- They can change their prepared spells after a long rest
- They can scribe new spells upon gaining Wizard levels
- They can cast rituals without expending spell slots
- They can use Arcane Recovery
- They can gain Spell Mastery or Signature Spell if they have the spellbook upon leveling up
If the wizard has the spellbook engraved in their mind, which of these things can the wizard still do, and which can they no longer do, if that same wizard did not have a spellbook at hand for some reason?