Also got to play some open beta this weekend. Started the download on Friday as soon as I found out about the open beta. It took me quite a while to get the game working though. I got the retarted stuck at 70% "Updating setup files..." bug along with some other problems. I finally got my game fixed by Saturday evening, was a huge relief to get it working, wanted to play it so badly!
Played the barbarian first off, cause it's my favourite. Barbarian becomes rather powerful, just love him. Played Monk as well, but still love my Barb better. The whole beta was pretty easy. I was never in danger of dying even once, so maybe they can make it a bit more difficult or something, will see what the retail D3 is like.
Also joined a few public games, just dropping in. Was really great fun to just take your character and go online and play with other people. I have a greater understanding now for why Blizzard made the game online only, something that pissed me off when I first heard it.
One of the big reasons I wanted to play the beta was to see what the latency would be like and if it would make the game unplayable, in which case I wouldn't buy it. So, concerning latency, my latency was usually between 300-400ms, which was actually fine. It (surprisingly) was not really noticeable. I would have thought 300ms to be way to high for playing diablo with. So playing on EU servers should reduce this to about 200ms I would guess.
To those interested, I have a 1Meg Uncapped line with Afrihost (IS). But like SnowWar said, the quality of the line matters. You can have a 10Mbps line, but if the quality sucks it won't help you at all. When I get home today, I will run a Pingtest to somewhere in Europe and I will post it here. Maybe the rest of you can do this as well, we should just all pick the same place to ping.
Right now I'm super excited about D3, cannot wait for May 15!