Got into the BETA a while ago through Blizzard opt-in program. Stoked too as I failed to win out of the 100 competitions I entered.
Played through with Monk and busy with DH now. Haven't had enough time to milk it, but having about 10-12 hours total played time, below is my feedback.
Telkom SAIX Account - 10meg line syncing @ 6meg - Decent rig.
Latency: Given the BETA servers are in the US and being pummeled by many players... If your latency is above 400 or so, the game becomes VERY annoying and everything has a delay on it. Most noticeable on attacks and looting. Much more noticeable than any MMO thats for sure. Every now and then my latency bar would drop to GREEN status (good) and I felt the game to be extremely fluid.. But it would change to YELLOW/RED not before long. I am hoping that we can somehow test EU servers somehow or that I can "test" what my latency will be like cos this is a deal-breaker for me. That being said I am pretty sure we'll be ok. When I used to play WoW on EU servers, my latency was between 280 and 400 without any proxy's / lowerping etc.
Mechanics: Given I have played mostly on the Monk, I really enjoy the gameplay and all the "advances" they have made. Destroyable everything, physics on most objects, movement, mob attack patterns etc. Its Diablo II improved to the max from a gameplay POV. I like the looting style and the items all feel like they belong in the game (given we haven't seen legendaries or set items yet).
Graphics: Meh, not exactly mind-blowing, but decent enough to have you drool now and then. You need to remember, Blizzard cater for the mass-market and couldn't go all Frostbite/CryEngine on us. The interfaces are awesome though. The bottom bar is unobtrusive (playing @ 1920x1080) and the only thing I would change or hopefully be able to move is the nasty chat window.
Overall: Unfortunately right now, I won't pre-order until I am sure I can play with atleast sub 400ms. Otherwise I won't enjoy the experience and given the amount of hype D3 has been building up, they heartbreak would be too bad to bare. Other than that, I can say that I am very impressed. Having played almost every Diablo clone in the past 5 years for atleast a few hours, this is still the grand-daddy of ARPGs. Lets hope the game gets released sooner rather than later and that latency isn't the biggest barrier to entry for us SA gamers.
(i would like to try MP sometime. please add me: Phatso#2511