Longer, more challenging and better soundtrack than the first part. Its amazing how such a brutal game where everything is based around killing can have such a deep story. You should play both parts. You will rage. You will want to quit. But you will always come back for more and you WILL finish it. You will hear one of the best soundtracks in your life. It may even make you sad when you understand the story. After you beat it you can challenge yourself further and attempt to beat it on hard mode (as if normal mode wasnt hard enough) or you can go for A+ ratings on each level. There is also level editor and you can get tons of levels from steam workshop.

Buy it. Play it. Enjoy it.