Well, the basic story is set in the near future where the technology exists to selectively wipe out memories. Ben Afleck is a reverse engineer. Companies hire him to analyze competitor's gear and design them something similar to get to market faster. Then he has his memory wiped so that his employer can't be caught for stealing secrets, etc. (Since he isn't doing a clean-room job, he's actually looking at the circuits and copying them, making some modifications - even today that's illegal. It'd be like one engineer at AMD looking at the traces on a Pentium and designing something to do the same thing. What you have to do is have one set of engineers analyze the hardware and write general specifications and tests, then another team does a clean-room design without ever seeing the other chip.) So the movie starts with him doing one little job just to show the audience the premise, then the main plot kicks in. An old school buddy offers him a BIG job - 8 figure payout, but 3 years of work. Normally he only works for a max of 2 months. So he takes it.
Turns out the job is based on stolen government tech and it is for a time television. :-) Not a time machine, but a time viewer - you can look into the future. He sees the terrible things the machine will be used for and decides it has to be stopped. So he mails himself a package of everyday stuff (his outgoing mail is screened, and his memory is going to be wiped, so he can't exactly leave himself a note saying "Your buddy is evil, stop him"). The stuff is a series of clues and items he'll need to get out of the situations he saw for himself in the future.
Some of it was a little much - he's an ubergeek who spends 2 months at a time locked in a room, litterally, but yet he's an uber-beefy jock with amazing fighting skills. He apparently spends his time between jobs training in staff fighting. Early on we see this - and you know that later in the movie he's going to have to kick some ass with an improvised staff. And he does. He's also very handy with a gun - I guess he also target shoots or something. :-)
There were a couple of SFX bits that struck me as too gratuitous, and made me think "Who the hell designed a machine like *that*?" "Why were those random pressured bottles just stuck on the end of those pipes - what did *that* accomplish?" But the one that jarred me the most was when bad guy #2 rips free a bundle of what is *obviously* fiber optic line and starts to strangle Afleck with it - and the sound effects were the classic hum and zap sound used for high voltage lines. It jarred me completely out of the story because it was so ridiculous to me. That and who uses liquid *hydrogen* to cool electronics?! I understand it had to be there to make the pretty BOOM for the finale, but it was silly. Liquid nitrogen, sure. Liquid helium, OK for extreme needs. Liquid hydrogen? Um, right... There are reasons it isn't used - not the least of which is that it makes a pretty BOOM when shit goes wrong.
The preachy stuff was about the evils of time travel and how man isn't meant to know what it coming, that seeing the future steals the future from you. How having the machine would create self-fulfilling prophecies. You see a plague coming so you gather up all the sick people and end up creating a breeding ground for plague. You see the stock market falling so you sell off your stock - as does everyone else, and the market crashes. You see a war coming so you launch a pre-emptive strike and start a war. That kind of thing. Not a bad point, and not surprising for something Phillip K. Dick wrote, but I felt they laid it on a little thick at points. Still, better than a Chriton "Technology is evil! Back to the trees!" sledgehammer.
The classic John Woo 'two guys talk while pointing guns at each other's heads' scene is in there. I read that Afleck is a big Woo fan and begged the director to put a scene like that in, and he did.