DiabloFans

I don't understand the argument that 'D3 has no replayablity because you don't have to start over to try a different skill.' Being able to change your build doesn't reduce the number of build available, it just means you can try a skill without starting over from the beginning again.
Yes, low level uniques aren't going to be in high demand. You can always try selling them of salvaging them to build new uniques. As it is you can start from scratch 5 times to play every class. If you really want you can do it 10 times, nothing's stopping you. The only difference is you are no longer forced to when you find out your build isn't optimal come inferno.
I'd rather have replayablity in end game content than in doing normal mode over and over in order to get to the end game content.

You'll only have access to the RMAH in your area. Yes, you can make characters in other realms, (like a NA player on a EUR server) but you won't have access to that RMAH, and won't be able to buy off your local RMAH and give to your character on that other realm. So you won't be buying off Chinese gold farmers unless that is your local realm. You'll be buying off the Texan gold farmers. ;p

I highly doubt it. If I got beta access with a pre-order sure, that sounds great, or if the money I spent for access could go towards buying it when it comes out. I'd even consider it if the money for Beta access ended up in your account for the RMAH as well, but to just buy beta access and then still spend full price for the game? Not likely. If it was cheap (like $5) and I could invite 3 friends to play with? That may be worth it, but I'd still be on the fence.

I don't think it was very common in D2 to have an amazon that used both the bow and the javelin skill tree. If you wanted both, you had to make two amazons, not switch between the two weapons. With that in mind the Demon hunter is a fine replacement for the 'bowazon' and if you were more a fan of the 'javazon' then maybe give monk a try.

If the old system was 'Runes drop all the time' then there really was no point, other than potentially making you wait a bit to be able to access the ability you want. I am all for less junk cluttering up my inventory, as that is less trips I need to make back to town.
I also appreciate that every level you unlock something, it makes each level mean something other than just some minor stat boosts.

I'm looking forward to playing with my friends. I'm thrilled with the Blizzard Annual pass because my wife loves WoW and now she gets free copy of Diablo 3, so hopefully she'll get into it and it will be a good co-op game for us. I used to enjoy playing gauntlet a lot with my friends, so it will be nice to bring back the whole 'Lots go kill a ton minions for loot and levels!'

If you're familiar with an area or boss ahead I could see switching skills ahead of time for that, but in the middle of adventuring? Possibly in Inferno difficulty if you're struggling, or if you get killed by a random elite that you need a specific build for. In normal you're just wasting your time.
Maybe later in the game once you've unlocked all your skill slots it could be worth your time to put 1 or 2 of them on CD and use the others while they're swapping, but that just doesn't seem likely to me.