Seeking Sanctuary: The Definitive Diablo III Preview
In Diablo II, potion-spamming was a guaranteed requirement, no matter what class you played. Available health regeneration wasn't nearly fast enough for primary healing. The game relied on two types of potions -- health/mana pots, which had a fast (though not immediate) refill timer, and Rejuvenation pots, which took effect immediately. Potions were a primary gold sink, particularly on troublesome bosses.
The need to watch your life more carefully adds strategy -- and you earn XP for playing things close
In Diablo 3, all of these are jettisoned, save for health pots -- and the latter are on a significant cooldown timer. The gap is somewhat filled by the existence of "Health Globes;" potion-like orbs that are dropped by dying mobs and automatically heal you when you pass near. Town portals aren't instant-cast any more, there's now a casting time attached.
These three changes have a huge impact on gameplay. Instant rejuvenation pots and immediate TPs made it genuinely hard to create a consistent atmosphere of challenge in Diablo 2, without resorting to cheap one-shot kill tactics (something we absolutely loathed and sought to avoid). The game now offers boosts to health/mana regeneration via gear attributes and through LAEK (Life After Each Kill) modifiers.
Unfortunately, life leech is still present and readily available, at least in the beta. This is something we very much hope Blizzard changes. The central problem with life leech is that it's a percentage modifier that can be stacked on gear and is dependent on weapon damage -- not base HP. It becomes an overwhelming heal that forces developers to assume everyone has tons of it, and to build the game accordingly. D3 was supposed to avoid this problem -- as of this late date, life leech is still hanging around.
As for Spellstuff regen, default attacks no longer drain mana, while Monks, Barbarians, Demon Hunters, and Witch Doctors all have specialized energy reservoirs, each with its own characteristics. Barbarian attacks generate Fury, which is spent using other attacks (this is roughly analogous to Warrior's Rage in World of Warcraft, for example), while Monks and Witch Doctors have a regenerating energy type. Demon Hunters are unique, with a quick-regenerating energy pool for some abilities (Hatred) and a slow pool for others (Discipline).
Better Structures Make For Better Games
I think Diablo 3 will be a much better game than its predecessor. Its foundations are better-laid, with fewer obvious pitfalls, while its skill and rune system is far more graceful than Diablo 2's talent trees. I'm wary of both life leech and the narrow XP/level scaling that the current beta offers, but the game is still in beta.
This may be the nerdiest darn thing I've ever said in a decade-long career of saying nerdy things, but I'm going to forgo pride and any chance of a date in the next 12 months and say it anyway -- better math makes for better games. Diablo 3 appears to be more consistent, better balanced, and more fun than its predecessor.