Well if you read the posts you get the impression that people loved it, only a few bad reviews in the bunch and a load of 10's. I dont really think using such a site is anything to go by, Its always the biggest games that get the most sales along with the most hate and trollers, no matter the genre. I have an old PC Zone magazine from when Diablo 2 was released and they gave it a 71% score, which is pretty poor.
I'l say it over and over, I think D3 was a great game that people expected too much from, I understand the frustration of wanting it to be better but a game that delivers in such a way rarely happens. The guys who are hating the most are the vocal minority and the general everyday gamers who arent posting around forums really liked it.
When it comes to arguements about online only and the AH, which happens to cover the vast majority of mad angry posters... Well as I've said countless times I think the AH was an excellent idea, you aren't forced to use it (even if it did seem that way at launch when the game was exceptionally difficult) and the online only merely reflects the way most people played Diablo 2 back in the day combined with the way Blizzard has gone with all of their battlenet games.
Fact is that an expansion pack will come sooner or later, everyone will buy it and the vocal minority will come on forums like this to whine, bitch and moan.