Ok, so I'd like to say something about the gameplay. I'm not a hard core gamer, I take my time to do things in game and I do not like competition. Also I'm not a good gamer, I enjoy playing but most of my friends play better than me.
Diablo has been and is a lot of fun for me. I started with Monk and currently I'm level 27. I'm 22 hours in, 18 of them to finish first to acts on Normal.
At first the game was ridiculously easy. Everything around just died when you merely thought of it. Haven't used a single healing potion for first few levels. The first death was the Act 1 Boss, I died to it once. In the Act 2 things started to pick up a bit, but just a tiny bit. However I felt that the choice of spells is... well limiting.
They did away with respecs in Diablo3, which I think is great. You can't practically respec in the middle of a battle, but pretty much anywhere else. You can at the same time use 6 spells, one of which is your left mouse click attack. So two spells go to you left and right mouse buttons and another for to 1,2,3,4 on the keyboard (of course you can re-bind). So out of pool of spells you have you can choose 6 at a time. All available spells are divided in 6 groups and in each group there are 3-4 spells. Each spell can be augmented by this spell specific rune. There are about 5 runes for each spell. In addition there are 3 slots to choose from the pool of about 15 passive skill that are not bound to keyboard or mouse.
The character build calculator can get a rough idea what it looks like http://us.battle.net/d3/en/calculator/barbarian
Of course skills and runes are unlocked gradually as you level up. There are not much to choose from on lower levels.
Also you can choose from one of the three followers, that also get unlocked in the process of levelling. I'm actually not quite sure what they are good for (anybody?) as their damage is about one fifth of what you are doing. They have four spell slots and in each slot you can choose one of the two given spells for this slot. There are also a few equipment slots for followers so you can give them a weapon, rings, necklace and an implement.
By the end of Act 2 I died probably 3-4 time, that is just before the battle with the Act 2 boss. Note, that I didn't really dwell a lot on the skill choice, every time I levelled up I briefly reviewed them and moved on. After I died 5 times in a row to the Act 2 boss, I had to think for a bit and changed my skills. This helped and I downed the Act 2 boss after a few more tries.
Act 3 started with quite sharp difficulty increase. I might need to re-think my skills again but in the first 4 hours of Act 3 I probably died half a dozen times. I also noticed that the battles became more interesting. This boils down to enemy group composition and how individual enemies in the group behaves. It is quite satisfying to figure out how most efficiently to deal with this or that enemy group.
Also by reading what other players write about playing on higher difficulty level it seems that more layers get added to the gameplay.
Also played about 20 minutes with a wizard and was dying a lot until realizing (duh!!!!) that you have to move as a wizard, otherwise you get 3-4 hits killed. When you start with monk, you just can be in the centre of enemy group and be hitting them at your leisure.
I see myself playing Diablo 3 for quite awhile.
Now the bad: Auciton house is... well. If the game was the same state as AH, it would be impossible to play. AH is literally unusable. Lot of weird glitches, unbearable slowness. Searches not always work. Bought items don't appear for hours. Sometimes weird sums of gold appear in the incoming list, that can't be transferred to stash. Often actions time out, and a lot of time the whole AH is down. If it was the whole product, I would say it's utterly broken.
Disconnects. Yes, not often, but if you just before the end of the quest after clearing a big dungeon, they are infuriating. So far I had to of these infuriating ones. I had a dozen of others which where more tolerable because I didn't moved far yet, so if they keep happening and resetting me I'd just put Diablo 3 aside for awhile until stability restores.
Always on sucks. DRM sucks. AH issues suck. The game is great.