The second one is pretty similar in terms of gameplay with some improvements in climbing and balance. There was some improvements on combat but I didn't think that was anything special for either game. The concept of weak points is interesting but I found it difficult to execute on most enemies.
The story is pretty good in the second one too. And there was a dlc for that one too.
I felt like the graphics were slightly better but just a tiny bit. The first was already decent.
The end definitely set up for a third act. Hopefully it gets made.
One of the main actors that plays an important (and favorite) side character passed away so I know that was something that could complicate things.