I tried the first one on 360 (borrowed a friend's copy), really enjoyed all the conversation-y intro stuff that was going on, and then got to the first combat encounter and all my AI allies kept running in and dying, leaving me to die, too, with no backup left. As far as I was able to determine at the time, it seemed like they were perma-dead, so I tried again. After about 3 rounds of this, I decided the game was far too hard for me and gave up.
I keep hearing they are amazing games, though, and I'm sure that I must have somehow misunderstood what was going on in that encounter. It's the first combat in the game, and the series to my knowledge has not built a reputation off of its difficulty, so I'd like to try it again.