I don't know if I agree with the first one being garbage, but yeah, they've generally gotten better over time, with Blood Money being better than the others by far. Absolution was a decent game, but it wasn't a very good hitman game. Didn't feel right, the disguise rules were a huge step back and the levels weren't anywhere near as good as blood money's.
This new one might end up being better than blood money though. So far I fucking love it.
I'm not sure how I feel about the challenge and opportunities stuff, but luckily it's easy enough to turn off. Levels are great, lots of stuff going on. My first play through of Sapienza took me about 5 and a half hours just running around everywhere.