[UPDATE] I've received an e-mail from a reader who has pointed me to a post by Blizzard Community Manager "Daxxarri", where he has a pretty big message that goes against the post below. He says that the game is in good shape, and that he thinks we will love Diablo III when it is released. He also adds that they want you/us/everyone to have high expectations of not only Diablo III, but all Blizzard-produced games. He also adds that if Diablo III wasn't a worthy instalment in the Diablo III series, they wouldn't bother releasing it, adding that that's the way they've always done it.
Take a look at the post here, which should calm not only my nerves, but your nerves, too. Thanks for the heads up, Andrew!
I've felt this for quite some time now, it started at about the time Blizzard were rumored to be working on Diablo III for consoles, but now they're actually coming out and saying that people should actually lower their expectations for Diablo III. Say. What!!! Direct quote from "Bachiok", Community Manager on Diablo III's forums:

There's only like 40 minutes of content in the beta, so that's pretty amazing you played for 7 hours. I hereby crown this game ... SUCCESSFUL!
On a more serious note, I too worry that we won't be able to meet the expectations people have built up for themselves. Part of my job is managing people's expectations, so... eh... stop it. Stop thinking about how awesome this game could be. Just imagine it's a new M. Night Shyamalan movie. Sure Sixth Sense was amazing and Unbreakable had it's moments, but this right here is the sequel to The Village ... or The Happening ... or Signs ... or any of the movies besides the two I first mentioned. So just like, lower those expectations, but still definitely buy the game please, and everything will be just fine. K?
The horse's mouth is directly above, and there's the quote. Seriously, they're coming Diablo III to M. Night Shyamalan movies? What are they thinking?! Are you scared that Diablo III won't be pants-movingly awesome? Or are Blizzard just doing damage control to the absolutely insanely dedicated fans that will go through this game with a fine tooth comb to find it's best, and worst bits?
We've also seen Diablo III's Senior Producer leave the company, which is also a worry.