Hmmm, regen thoughts.
I have two very different views on this, but they end up coming to the core issue.
I love Demon's Souls. I loved the challenge, the brutality, the always thinking about every step of the way and planning things out, learning from my mistakes. The sense of accomplishment that comes from that level of challenge is great and rare in gaming today.
The other side- the battles in FFXIII. I know, linear, story blah blah. Strictly from a combat perspective. The level of tuning you can do to *every* encounter is significantly higher when you know the player is going to walk into combat with maximum resources. Obviously being a TBRPG this is a very different approach, mechanics wise, then you could reasonably take with something like a FPS or even a dungeon crawler. Compared to Demon's Souls, FFXIII is considered an absolute joke in terms of difficulty. That said, Long Gui is *far* more difficult then anything in Demon's Souls(forget Vercingetorix). Obviously overall Demon's Souls is a far more challenging experience, but due to the health regen used in XIII any given encounter can be tuned to a much higher degree of difficulty.
What the two different perspectives come down to, and I appreciate both, is balance. If the game is designed with regen so they can make it more punishing per encounter, I think it *can* be an asset depending on the flow of the game. If it simply tacked on to make things easier, which seems to be the norm, then it is a detriment to gamers.
That is my take on it anyway.