I've played Diablo II for about seven years or so, and if there's one thing I still clearly remember out of it is that on Normal difficultly it wasn't "fun", I still clearly remember telling myself "I hope it gets better later on" the first few months when I used to play it (and that was off-line). Well, to give some credits where due, the ONLY three parts I really had a challenge on Normal difficulty in Diablo II were Normal Duriel, Normal Diablo and Normal Baal's Throne Room (fifth wave, the unique minions with Lister the Tormentor). Those three fights on Normal could be lethal in no time, even with good preparation, especially off-line, but other than that for those out there who think that Diablo II on Normal was "much" better than Diablo III is right now on Normal... well... they need to go play DII on Normal again. The actual fun and real challenges start on Nightmare, and Hell is where it's all at. I suspect that Diablo III follows a similar challenge progression through its difficulty settings. I fully expect dozens more mobs on-screen on Nightmare at pretty much any given locations as it was in Diablo II's Nightmare when compared to Normal. The number of unique mobs grouped in packs of dozens will be a blast to get past through. Then there's Hell and beyond. So far I've played the Beta for about 2 hours with a Barbarian and it does feel almost exactly like Diablo II was, and to be honest I did NOT want Diablo III to feel too different from Diablo II. Why fixing something that ain't broken? Diablo II still endures a decade after its release, heck there's ANOTHER Ladder reset coming May 2nd, yes, for Diablo II, it's still being played by a lot of people out there.
With that said however, there's still that one thing that does bug me about Diablo III, but I'm not "obliged" to use that feature, and it's of course the whole auction house with real money thing. I do wonder if over time people using that will have "unfair" advantages compared to those who only use it with in-game Gold or trade methods without spending a single real-life dime on that. Time will tell. To be honest even when I used to play Diablo II daily for years I still mostly locked myself in my own created and passworded games, and I very rarely created games opened for the public to join in unless I wanted help, or felt like it for some reason. If I feel like I want to play alone I can still do it and I am very pleased to see that it's still possible.
One major improvement for DIII's multi-player is of course the player-specific loot tables, so that when something - anything - drops it's for you and only you. The one main reason as to why I mostly played DII alone for many years even when I had my characters on-line only is exactly because of player-specific greed, pretty much all having to literally go on the hunt and "steal" other's loot even if their freaking name wasn't written on the item. How many of you playing DII on-line "lost" items that "belonged" to you because YOU killed the mob(s)? And some random Joe would run at it and just happen to click faster than you could or just happened to press Alt before you did to see what was on the ground and picked the item(s) up even though you saw it too? Was THAT frustrating? Hell yeah it was, don't tell me it wasn't! And most of us have done it, either on purpose, or just out of reflex over the years, the very game's loot system demanded such behaviors, otherwise you'd better just play alone, which is what I did (ironically, it augmented my challenge because of that, mostly relying on myself and self-transfers with mules and barely any in-game trading with others even when the currency was Stone of Jordans). With Diablo III, if you DON'T want to play with others then the reason cannot be due to the fear that others will run at "your" items anymore, and that reason ALONE makes DIII a lot better than DII as far as multi-player is concerned.
The only "competition" that DII can offer to DIII from this point is anything but multi-player related, and there's probably not much anymore, since DIII is pretty much DII refined, but refined doesn't mean perfect, no games are, and DII wasn't either. I know there's a few things I won't like in DIII, like in any other games there's always something I don't like. But for the moment I do like the game, it reminds me of Diablo II as I said, and that's just awesome for me, I didn't want DIII to turn into something else than a Diablo game, namely an action RPG with minimal thoughts involved and lots of grinding and looting, it IS what I wanted out of it. If I want something more complex, more story-driven with an actually good written story, with great text-based dialog or voiced dialog, with emotional involvements, I'll go play something like Dragon Age, Witcher, Planescape Torment, Baldur's Gate, and so on. Not all RPGs have to turn into a new Shakespearean play or a masterpiece and contender of story-telling lasting for 80 hours of game time. I'm fine with DIII's action and fast-paced story progression, as it was with DII, no need for a wannabe epic journey in third-person trying to be something that it shouldn't be. From what I've seen and so far played, it seems promising.
I'll definitely buy it on release.