Whoa. They don't make a lot of movies like this. Set your adrenaline meters to 11 and hold on. Tony Scott is a master director, and although I don't always like his movies, they are always well constructed. With Unstoppable, Scott assembles a talented cast and tells a good story at high speed.
The plot is simple: due to a combination of bad judgment and bad luck, a long train with dangerous cargo heads toward a densely populated Pennsylvania city with no engineer on board. Dashing engineer Denzel Washington and barely adequate Chris Pine (the new James T Kirk) try to catch up to the runaway on another train. Thrills and spills happen, yada yada.
What I liked was that the movie didn't cheap out. It explained the inner workings of railways enough so that the audience knew the stakes, and fleshed out the characters enough so that we enjoyed their company. I was happy to overlook the implausibilities because it over-delivered everything else. For example, in some of the scenes where the train is supposedly going 60-75 mph, it doesn't look like it's going anywhere near that fast, or, for the entire length of the train's run, a railway guy in a red pickup is keeping tabs on it. They make it look like he's been driving along side the train most of the way rather than on the nearest parallel highway, which is more likely. Whatever.
Think of Unstoppable as a worthy companion to 1994's Speed. Unlike 1997's Speed II.
On a person note, that's number 90 for the year. 10 to go to hit 100.