All it does for a wizard is allows him to scribe one extra spell in his book for free on that level up*. That's it. (kind of a waste of a feat, huh?)

On the losing your spell-book issue, there's at least some mitigation in the fact that you can expend the spells you have memorized at the time to scribe a new book containing those spells at half-price.

*Unless you buy the absurd interpretation that it lets you learn -any- one spell up to one level lower than your highest.