I can't recommend it, even though it has potential (and it is fan made), but there are a few reasons I can't recommend this.
1) Its just 3-4 stock areas with at least 300-600 enemies each map.
2) Even on the hardest difficulty the game is easy.
3) It looks like just one level from each game and all the weapons unlocked in each map.
I love the Painkiller series, and I love the fact that this is a fan-made game, but like I stated, it has potential. Perhaps some polishing and more variety and it'd be much more enjoyable.
It pains me to say, don't buy this. You are better off playing Painkiller: Black Edition, well worth the money and it has the most levels out of all the painkiller games.
Now, keep in mind, I played and beat Black Edition twice, and that is probally the best (and hardest) out there on normal. I played this on normal and it was easy.