So where am I in the beta? I'm on my fourth play through. The beta is rather short, just a couple of hours until the final boss and a message that you have beaten the beta. I played through that twice with my first character, the barbarian. First time got me to level 9, second time to 11. There doesn't appear to be a hard level cap in the beta, but there are obviously diminishing returns by playing through the low level content repeatedly. Nevertheless I like the concept that you can at any time jump back to a previous stage, keeping your character and only losing story progress voluntarily.
The barbarian is a solid melee character, and I especially liked his leap attack which can also be used to overcome some obstacles or jump *out* of combat instead of into. The second character I played was the monk, and in many ways that one was even more fun to play as melee character as the barbarian. The monk is a bit more difficult as he uses active healing compared to the barbarian's passive healing abilities. But the monk clearly has advantages with his melee attacks having a better range and hitting several enemies. The barbarian is probably better against hard-to-kill boss mobs, but most of the time you are dealing with large amounts of low-level mobs, and the monk dispatches these with less clicks than the barbarian.
My fourth play through with the third character is with a witch doctor. Frankly, I don't like that character. I've never been a fan of the indirect combat of pet classes. Furthermore in Diablo III you not only attack a lot of monsters, but also plenty of barrels and other containers. And you do that by launching your standard attack with your left mouse button on the barrel. It isn't as if that doesn't work if your standard attack is a haunting curse or throwing poisonous toads, but opening a barrel that way feels very silly. Another disadvantage I see with the ranged classes is that your main healing comes from walking through the health globes dropped by enemies you kill. That works very well in melee, but for a ranged character the health globes drop far from where he is standing. With the witch doctor the health globes mostly drop wherever your zombie dogs decided to attack, and you don't really have much control over that. I'll have to play the other two ranged classes to see if that works out better for them.
Betas in general often evoke the old discussion about what they are good for, with one side claiming they are for play testing, the other side seeing them as a marketing tool. The Diablo III beta is clearly on the marketing side of things. You only get to test a short part of the game, encouraging you to buy it to see more. I consider that valid, unless you run into a case like Age of Conan where the content *after* the part you could see in the beta was completely different from the part the beta showed. I don't think there is much risk of that in Diablo III. On the game testing side I honestly wouldn't know what I could "test", the game is already extremely polished. I could imagine Blizzard testing server capacity when the beta goes public, but other than that there is not much of a job for a potential beta bug tester.
Is the game any good? More and more I find that this question very much depends on what you expect. For example the other game I tried this weekend was Adventure World, a new Facebook game from Zynga. Which is brilliant *compared to expectations*, that is "for a Facebook game". Diablo III is undoubtedly much better than most other similar games, but then expectations are also much higher. It is very close to the best you can get out of an action RPG game with random dungeons. But it still suffers all the inherent disadvantages of an action RPG game with random dungeons: The deja vu of walking through the same building block of the random dungeon several times; the endless clicking on stuff; the ups and downs of random loot. If you loved the previous versions, you'll love Diablo III. If you played through to many Diablo clones in the last decade, Diablo III isn't going to offer you a fundamentally different experience. Just a more polished and cooler version of the same.
My biggest surprise in the beta was how closely integrated your different characters are. They not only share a bank, but also their gold, and even their crafting skills. Due to the crafting and the sharing of random loot, playing Diablo III with several alts is quite an attractive option. You *do* play through the same story several times if you have alts, but you'll find a lot of pages of training that way, which are the "skill increases" of Diablo III crafting. I do like the crafting system, where you disassemble unused items into essences and reassemble those into the items you want.
Although the auction house isn't switched on in the beta, the crafting and exchanging items between alts made it clear to me that the discussion of the auction house has been focusing on the wrong problem. Everybody was only discussing money, and gold farmers, and Blizzard's share in that. But the more fundamental issue here might be difficulty level. Now I can't say much about the final difficulty level of Diablo III based on the beta, which is said to be rigged towards even easier, and only offers the lowest difficulty level of "normal" and the lowest levels anyway. But I noticed the huge difference just twinking your alts with crafted and previously collected gear makes, and can only imagine how much worse that gets if you buy the really good stuff from the auction house. As far as I've read, you need to play through each difficulty level to unlock the next one, and then the higher difficulty levels hand out better loot, which make the game easier again. That is already a strange cycle for a single player with a single character. But if you add the possibility of characters on normal difficulty level wearing gear collected at "inferno" difficulty, you risk making the experience completely trivial. I can already hear the arguments of people claiming they need to farm gold to buy stuff from the auction house to enable their alts to play through the lower difficulties faster and get to the end game "where the real fun is". That fallacy of doing stuff you don't enjoy to make a large part of a game too trivial to enjoy, in the hope of getting faster to more fun at the end is already doing great harm to World of Warcraft. I'd hate to see that repeated in Diablo III.