It actually wasn't that bad. I saw it, and there are a lot of things that I disagree with in the review. First off, the plot twist isn't obvious. At all. I've seen all things horror, good and bad, and I can usually see these things coming from the beginning of the movie. But I was genuinely surprised at this one. Yes, the toast thing is a little stupid, and admittedly his whole speech surrounding the toast thing was stupid. But there's actually two things that happen before that which would elude to the devil being involved, the toast thing isn't the deciding factor. Also, I felt that the Latino thing was a little stereotypical, but there's truth behind stereotypes. They don't just pop up on their own merit. There's some philosophical bit that pops up at the beginning, as the Latino guy is narrating, that is mentioned in the end and I thought that was pretty cool. And now that I think about it, the movie does a very good job of sewing up all the major plot points. Anyone who's seen a recent horror movie knows that most of the time half of the plot points go unmentioned again, but that's not the case in Devil. Everything has an explanation, except for this one part where a walkie-talkie appears in the elevator. But you can make an assumption, which isn't a huge stretch considering what happens to the elevator service man, as to how it got in there. There is one plot twist that you can see coming, involving the man in the business suit and the detective from the police, that you can kind of see coming, but it's not one you can see coming from the beginning. It only becomes apparent in the ending scenes of the movie. Honestly, that was a point mentioned in the beginning which I thought would be a horror movie cliche' of never being mentioned again, but I was shocked when it actually did come up later.
All in all, it's not that bad of a movie. It's not the best ever, but it's not horrible either.
OT: What bothers me is that most of the people on this thread making all these assumptions haven't seen the movie. And it's very clear with the first two pages littered with "LOL, WHO BRINGS TOAST ON AN ELEVATOR?". So maybe you should consider watching a movie before you make yourself look like an ass.