I tried number 2 and it just didn't work for me. All the mechanics seemed better if looked at it in their own but they didn't seem to fit as well as in number 1.They completely changded the combat system between Thea 1&2, so you could watch a bit of each in action and see which you prefer. I preferred the system in 1 myself, but it's more of a "card game" than 2. The rest of the game is largely the same in how they play. And no, you don't have to have played 1 to play 2.
Can't really explain it.