The open beta started yesterday. Everybody with a Blizzard account (doesn't need to pre-order D3) can play. Download it and give it a go (I think the open beta ends either tomorrow or the day after) if you're interested. Blizzard has a very well-thought-out downloading process which employs p2p transfers and permits play even when you've only downloaded less than half the game.
Don't have time to play this myself.
If you play on multiplayer, getting through the beta content takes less than an hour. It's hard to judge what the game will be at launch. There are a lot of hints on the Auction House page indicating it will be a fair bit more complicated than it is, which I think is - now - pretty simple (less the graphics taking physics into account, which are pretty nifty-looking), and very easy relative to Diablo II - but again, since it's only a portion of the Act I which is available on beta, it's hard to say. The Auction House wasn't working properly when I played yesterday, either, making it more difficult to gauge what D3 really "is."
