In this past week, I've gone to see both I Am Legend and Margot at the Wedding and enjoyed both greatly. They're rather different movies, though. Margot struck me as a bit worse than The Squid and the Whale since Jack Black slightly took me out of things by hamming it up, but it's otherwise really good. Just a couple of days before I went to see it, I caught the lamentable Invasion on a plane flight but Margot completely redeemed my views of Nicole Kidman.
Legend, as I understand it, departs massively and systematically from the book, so if you're a fan of the book and expecting an adaptation: Don't. But its vision of post-apocalyptic New York is brilliantly executed and I don't want to say too much about it since I don't want to ruin the suspense. Naturally, when you look back there are some plot holes, but that's kind of what you get with this genre.