Based off the beta, I'd be inclined to give the game 8/10. It's Diablo. Doesn't do anything groundbreaking, doesn't drive its genre forward, doesn't contribute anything new to gaming, doesn't have a brilliant story.
However, it's a new Diablo, and I'll play it for MONTHS to come, and not completely put it down for years. Some games are just review-proof, and great regardless of objective quality.
I would say that the skill runes are actually a pretty dramatic departure from skill trees, and a step forward for not only the specific ARPG genre, but RPG games in general as a means of handling character combat progression/customization. It's a pretty solid system.
The RMAH is also somewhat ground-breaking - being one of the first (second?) major Western titles to do something like that (I would argue TF2's hats are similar enough, and they came first), as well as controversial. It's not quite the same as typical cash shops, since all goods are player-generated - Blizzard just skims off the top of everything. The capability to cash out to PayPal directly is unique though. With TF2 hats, or anything else, you have to cope with the risk of directly dealing with other people to cash out like that.
Aside from those two things though, the game probably isn't particularly "innovative" besides the massive amounts of polish Blizzard layers on. (There's a Jay Wilson interview about this, saying how a game the Blizzard philosophy is that a game that is very refined
is innovative, and that Blizzard would rather make (and play) well made games, than "innovative" games with new features, but aren't executed well.)