I saw it Saturday. It was very good, though it did avoid the subject a vampirism as described in the original book. The violence was not excessive nor was it graphic. There were a few "gotchya!" moments making my wife and a few others start. It is certainly worth the matinee price, and I would not have been disappointed had I paid full price or waited and bought the DVD when it comes out (this is one gauge I use, would I have been disappointed had I bought the DVD?). The depiction of an abandoned New York City is eerie. All in all, I would recommend it.
The 1964 Vincent Price version, The Last Man on Earth probably stayed closest to Matheson's book, while the 1971 classic The Omega Man with Charleton Heston is closest to this current version. Make no mistake, however, I Am Legend is very good and much better than the previously mentioned films.