I've heard mixed reviews about The Expendables. A lot of people liked it, a lot of people didn't. Here's my advice: Don't go to it expecting some complicated, thrilling plot. It's a Stallone movie. Expect lots of shooting, explosions and cheesy lines.
In my mind, those three things can make up a great movie for entertainment purposes. I'm a huge fan of Jason Statham and Jet Li. Those two in the movie was enough for me to go and see it. I'm also a huge action movie fan. After a rough day, nothing beats watching a pure action flick that can make you laugh, curl your toes and say "omg that just happened" or "where the hell did that gun come from?"
There really isn't much else to say about it. It's entertaining, it's gory, it's far-fetched and completely awesome.