I managed to get through all of the classes, at least long enough to figure out the basic mechanics of the class, and whether or not the class was going to be something that was fun for me to play. So far I definitely like the Barbarian, the Demon Hunter, and the Monk. The Witch Doctor is interesting, but I don't know if his interesting-ness is going to be enough to make me want to continue to play through the entire campaign, or if it'll just get campy. I didn't like the Wizard at all, which is kinda odd because I usually love mage-type characters.
A few things do annoy me though, especially the whole weapon type doesn't matter thing. It didn't really click until I was playing the wizard and I was running around with a hand axe and a shield, which just seems so wrong to me. Clerics should be allowed to use shields and maces, as well as staves, but wizards ought to be limited to staves and daggers and possibly a wand as an off hand weapon (or at least, that's what my 21 odd years of playing Might and Magic have taught me). Also, the idea of crafting is a little bizarre, but it does give me something to do with the random magic items that are meaningless for my class, and I like the fact that (at least up to level 2 blacksmithing) they've left the enchantments random. Sure, you can keep breaking down crafted items if you're playing a Barb and crafted a helmet with +8 int and +2 yard radius of gold pickup, but you only get 1 essence from breaking it back down. My only big concern with crafting is the "stash" mechanics. At least in beta, items I put in my stash on my first character, a male Barb who topped out at level 9, were in the chest when I logged in on my sixth character, a female Barb that topped out at level 10. They were the yellow fangs that you sometimes get from salvaging rare items. I don't think he had any of the normal blue essences in the chest, but if you can pass enchanting items back and forth like that, you can really OP a character on your second pass through. Of course, in single player play, the only person you really cheat by doing that is yourself, but I'm not sure how it would play out in multiplayer play, or if it would have any sort of impact on that real-world money auction house, or even if it's going to carry over into post-launch play.