Actual game discussion ahoy:
I was a pretty long time fan of D1 and D2, and after hearing about various changes that have been meticulously debated in this thread, I was hesitant to buy it. Ended up caving for various reasons, but that's neither here nor there.
However, here are my impressions after making it into Hell difficulty:
Yes, the story is pretty bad, pretty generic, and the "twists" you see coming from miles away. The quest names even give away what is about to happen in the storyline. If you're a real lore fanatic, best not think too hard about it.
The game, for better or worse - is "streamlined". This means things like tp and id scrolls are out, and you merely press a button to warp to town as long as you are not under attack. You don't distribute your character's stat points, instead it's based on character class and much more item dependent.
Your weapon damage means everything... EVERYTHING. Spell damage is now tied to weapons, meaning that if you aren't geared up properly, you're in for a bad time, or at least slower time. Always get a better weapon.
I tried every class. None is as broken as the monk. Buff and heal the entire team, and get several in a group? Welcome to never die town! Normal difficulty was a joke. Bosses that tore me and my friends to shreds with other classes in nightmare and hell (I'm looking at you goddamn purple laser/desolation/molten bosses) were suddenly manageable with team heals and party wide buffs.
And how are they so broke? Well, with skills like Transcendence which is arguably the best passive in the game (heals for a stupid amount when you spend spirit, which you get for hitting things), and the fact that their stat -dexterity- for damage also gives them incredible survivability (dodge) and synergy with another passive like "Seize the Initiative" (for massive armor) you can tank with the class that is supposedly a glass cannon. Just stack dex items.
And the whole point of diablo has always been hitting harder and faster, and that's essentially what the monk does. You can stunlock 99% of mobs around you, gaining resource spirit energy, and then blow everything away.
I don't want to turn this into a monk supremacy rant, but the whole point for bringing this up is what I spent a lot of my D2 hundreds of hours on... pvp.
I simply don't see how Diablo3 can be balanced for pvp while maintaining pve balance. "One with everything"? Just stack one resist and take negative damage. There are other skills that stunlock forever. No bueno.
The witchdoctor is a class that I was iffy on at first, as I want my necromancers back, but ended up being one of the most fun to play.
The Auction house is a pretty cool addition. I can't speak for the Real Money Auction House (tm) that doesn't launch until next week, but the current AH, when it works, is great. It makes a game about finding loot really about OCD finding the perfect gear.
I had more fun with the Act2 boss battle than Act4, but Act4 was pretty awesome. A total dream come true.
Also, the "hidden level" is absolutely hilarious.
I just got out from another night of playing and it's almost 6am, so I'm going to leave with that semi-coherent rant.
But seriously, monks are too ridiculously good/have much more utility in relation to the other classes. Try them.