A promising concept, in the end, it somewhat lets you down. The first half an hour was extremely boring, you would be surprised at how the beginning, which should have been a blast to the senses, can seem so bland. What's more, after that action sequence, it goes downhill with a lot of dialogue, but not a lot of things happening to move the plot along. It takes a long while before the movie gets interesting enough for you to not let your thoughts wonder. Some of the characters' actions are questionable and their motives are often not entirely clear. As you'd expect, the big explosions and gunfire at the climax is the most exciting and visually spectacular part of the film, but it doesn't make the scenes before it worth it. The film doesn't seem to pick up much, the plot is very basic, more so than you would expect. It just feels... uninspired. Surprisingly, there is some humor scattered around, giving you a chuckle here and there, breaking the monotony of everything else. The best thing going for The Expendables is the cast.
On a separate note, this post is a big milestone... my 1000th post. Yeah, so much spam... :P