The Expendables 2 has a more engaging plot than it's predecessor, such that it doesn't feel as much of a chore now to watch through the whole movie. The first forty minutes or so were still quite boring though, but once the murder of one of the team has happened, things get better and better really quickly. The movie starts off with a typical random action scene with guns blazing and a lot of explosions. However, it still manages to feel generic and fairly boring, thankfully that tone doesn't continue through the rest of the movie. What made this The Expendables 2 superior to the first movie is that there's a good motivation for you to keep watching. The injustice of the situation, fuels your rage and you want to see the antagonist gets what he deserves. Sure, it's not original, but it works well here and keeps the movie going. One of the recurring things though is big name actors come in at random times to save the day, it feels awkward and forced. If they could have incorporated them more naturally, then it wouldn't break the immersion as much. There are also a small number of crazy events that happen which makes you stop and question the possibility of it. This movie is way more fun than the original and well worth watching.
