WARNING: Possible Spoilers
First off, I don't have a clue why this movie rates so low everywhere. Honestly, I don't understand it whatsoever. Okay, so it's not Oscar worthy, potential classic or mind-bendingly original, but it's certainly not as bad as everyone seems to be making out.
I've read reviews claiming that Timberlake's performance is the worst they've ever seen. Seriously, they couldn't have seen much bad acting if that's what they think. It's competent and believable, void of any awkwardness that some films are plagued with through lack of chemistry and/or generally bad performances.
I swear I must've seen a completely different film to everyone else. Morgan Freeman and Kevin Spacey have quite pivotal roles with plenty of screentime, by no means minor characters, and their acting isn't as low-rate as everyone's making out. This film is very plot and suspense driven, despite the lack of plot revelations and in-your-face action (although there is some of that at the end).
I've also read of action sequence plotholes such as Timberlake's character, although never having fired a gun before, fires it perfectly, and when he runs out of ammo, 2 more cartridges appear from nowhere - Timberlake's character holds an uzi for about 2 seconds and he never fires it. LL Cool J's character never has any moments of magical ammo, although the one man against an entire police department is a little far-fetched.
All-in-all, it's actually nowhere near as bad as people keep making out. Give it a try before you knock it.