From watching YouTube videos, it appears to be far closer to Splinter Cell Conviction than any Hitman game. I'll happy admit that I haven't played the game, but still Absolution looks almost completely unlike a Hitman game.
It is much closer to a (bad) splinter cell game than Hitman. There are 20 missions (4 take a total of 20 minutes though) but many of the missions are split up into 3+ areas with checkpoints. There are maybe 3-4 traditional Hitman areas in the game and they are extremely small with not as many creative kill options. The rest of the game is split up into a bunch of splinter cell-ish areas with way too many guards in each tiny area. This wouldn't be as big of a problem if the disguise system wasn't completely broken.
Like I said you're not even going to get a good stealth game out of this let alone a good Hitman game. It's really not worth the money and time.