I saw it today and I liked it. For the record, I think the original is a great movie but I never quite got into the hype, as I wouldn't even put it in the top 5 of best South Korean movies in the last ten years, nor do I consider it Park's best movie.
Regardless, the original was a great movie, and in the end I found Spike's remake to be a decent well-made thriller. The first act (Joe's imprisonment up until his release) was as strong as the original's and the highlight of the movie. The build-up is excellent and Spike hits all the right notes. The second act to me however felt a bit sloppy, and I felt that's where most of the studio involvement took place. The plot's a bit too jumpy and character development comes to a screeching halt in favor of pushing the plot forward. The third act, which contains the most changes, goes a bit over the top (in one way it even outdoes the original in absurdity) but I felt tingles all over again at the climax so no matter what people say, Spike did right by the original.
I also thought Brolin and Olsen were great in it, and I feel many people downplay that. Brolin especially, this is easily his best role after No Country For Old Men and it's like people don't even care. Speaking of the cast, I thought Sam Jackson was the weakest link, pretty much coasting through his role and lacking any form of (the sorely needed) intensity. Even Copley's slightly misguided role, zany as it is, worked better.