The best way to see The Town would be without having seen Heat. If you can pull that off, you'll have a much better time with the material. You may also want to skip Good Will Hunting and Point Break while you're at it, just in case. Ideally, the Boston pastiche, the visceral thrill of bank robbing, and Ben Affleck's steady directorial hand will thrill you, not cause you to focus on your minor quibbles. I'd say that's really the least you can do for the man who was in Armageddon; responsible for a much-needed rethinking of the importance of animal crackers in our everyday lives.
Now then, the story of The Town is the story of Charlestown, Boston, a historically infamous bank-robbing locale. Ben is an up-and-coming criminal with a crew; Jeremy Renner is his stalwart and heavy-hitting partner. Two other guys are on the team, but they aren't really featured. One is the wheelman (gotta have a getaway guy) and the other handles IT and communications. The film starts sans opening credits, bless it, just starts with a bank robbery and we're off and running. The gang looks and feels technically proficient and things go off relatively hitchless. Except for one minor problem. There might be a witness.
Enter Claire Keesey (Rebecca Hall), potential witness, who Affleck is sent to suss out as to her recollections. Is she going to get them all thrown into prison? She doesn't know much, but she remembers a few key items, and she's also wounded in a way that draws Affleck to her. That's enough spoilery activity -- we'll now proceed directly to the strengths and weaknesses of the film.
What doesn't work about The Town is how little new ground it breaks. You've seen elements of it in films before, so this admittedly updated and glossy version doesn't feel particularly innovative. Bank robbing movies come down the pike every year, and to stand out they need to do something special. The Town, for the most part, doesn't. Jon Hamm is largely wasted in his portrayal of an FBI agent; he's a one-note character that doesn't feel fleshed out. Pity. There are also a few key plot points that are simply not resolved, and as the film culminates you might find yourself saying, "But what about..."
What does work is Renner, as Affleck's pal, and Blake Lively as his former love interest. You've never seen Lively this gritty. She's quite effective with a thick Boston accent and even thicker dark circles under her eyes. Renner sells the tough-guy persona to perfection (as opposed to Affleck, who might have gone Hollywood over the past few decades). The bank robbing scenes are relatively compelling, and the film is certainly not lacking for firearms or car chases. This is a solid two-hour ride at the cinema, not overtly challenging or dynamic, but not riddled with problems either. If The Town was a bank heist it would get away with all the cash in the drawers and a few of the safety deposit boxes, while just missing out on the "once in a decade" score because the heat was closing in.