This was basically 70% of a really really good movie and 30% of simply terrible. Will Smith really brings something to the table of this film. His performance is surprisingly good (considering the material) and he has really grown a lot as an actor in recent year, especially in the realm of facial expression. The early scenes of the film (basically a day-in-the-life in post-apocalyptic NYC) are really wonderful. The designs are convincing and, frankly, amazing and are truly deserving of an IMAX viewing. The last segment of the film, more zombie/vampire focused, is unredeemingly awful. The flashback scenes to the disease outbreak are very effective, if somewhat manipulative. The villains, a mash-up of zombie and vampire traits, are the worst part of the film. Rendered in piss poor CGI that often seems ripped straight out of 1999's The Mummy, the creatures are neither frightening nor believable. Recently 28 Days Later and 28 Weeks Later have had similar running zombies that are far more effective when rendered with actors and make-up. Alternately, The Descent (maybe the best horror movie of the last 15 years) used male ballet dancers to craft almost otherworldly movement patterns to tremendous effect. Just because we have the tools of CGI, doesn't mean we NEED to use them constantly (plus less CGI would keep budgets down). Star Wars, done largely with scale models, still has more effective visual effects than a huge number of CGI heavy films, Francis Lawrence should learn from that. This could have been so much more. The later action scenes are surprisingly inept (especially considering that Lawrence's prior film Constantine at least had workable action segements) in design and editing. They underuse a truly great performance from Will Smith as well. In one scene, about 2/3 of the way through the film, the film camera focuses entirely on his face during a difficult moment: the effect is astounding and truly moving. Additionally the ending is relatively miserable as is a late introduction of religious themes. The early designs and premise are so great (I think I'd have enjoyed a two hour movie of just Will Smith's life in empty NYC quite a bit) that it makes the poor creature design and weak concluding chapter stand out all the more. It's worth seeing, just temper your expectations from the awesome trailer.
Overall Score: 6/10 (seen on IMAX, possibly a 5 on regular)