I am legend was done very well. A lot of people have slated it, and while I think it's not fit to polish 28 Days Later's boots, it's nowhere near a worst film ever candidate.
Will Smith is excellent in it, for one thing, that and "Pursuit of Happyness" have convinced me that he ain't a half bad actor after all.
My main complaint is that the zombies/mutants just weren't that scary. They looked like a bunch of crackheads.