Instead of suffering a broken leg, our protagonist is on house arrest, complete with alarm on his ankle. This is both a strength and a weakness. It makes the story a little more mobile and allows the filmmakers the freedom to do something different. It also breaks down the sense of tension and claustrophobia that Hitchcock worked so hard to build.
Fully intact, however, is the key theme of voyeurism. This is most obvious while Kale is spying on the girl next door, who always seems to be lounging around as if someone was watching her. More telling, though, is the stakeout full of computers, camcorders and cell phones. This update allows for some interesting uses of technology. The 1954 classic, by contrast, had barely so much as a TV.
As remakes of Hitchcock masterpieces go, this one is actually pretty good, at least until the climax devolves into a slasher flick. It certainly has a lot more life to it than Gus Van Sants by-the-numbers reconstructing of Psycho. There isnt a lot of true suspense (almost everything turns out exactly as it seems), but the cast and crew clearly are having fun taking the premise as far as it will go.
One original idea the screenwriters had was to use the voyeurism angle to take a swipe at homeland security. As Kale is building his case against the presumed psychopath, he shouts, "Why does he want his privacy?" It may be wrong to spy on your neighbors, but who's spying on you?