There are lots of books out there. Big books, little books; fantasy books, science fiction books; optimistic books, dystopian books. Legend doesn't do a whole lot to add to the collective definition of 'book'. It's just a book. But it's a pretty decent book.
From what I can tell (based on other stuff I've read), Legend is a fairly typical 'optimistic' Dystopian future. Things are crap, sure, but so far it certainly looks as if things can (eventually) get better. The writing is solid, and the world feels real. All of the characters are well-built and understandable. The plot is respectable, if a little incomplete-feeling, but that turns out to be okay. It won't be completely unfamiliar to people who've read 1984 and Brave New World, but it's also different and distinct from those.
The books biggest problem is that it's not terribly strong, and so it suffers a lot from its few weaknesses. Most notably, the descripto-blurb in the front cover spoils the most interesting part of the book. Unfortunately, the way said blurb is written, it pretty much has too to make it interesting.
Legend is apparently the first book in a planned series, but it's got one of the best sequel-hook endings I've ever seen. How it wraps up, I'd enjoy seeing more of the characters, but I'm not terribly desperate to get more. I consider this a good thing, as it allows the book to stand fine on its own, something some other such sequel-hooks leave a lot to be desired at.
Final verdict: F'naa. It's a fairly good book, all things considered; and if you're in need of something to read but only have limited options, it's a solid choice. However, it's not a good book, in the more conventional sense, and it's not worth going out of your way for. 7/10