The login problems were damn annoying. Blizzard could do what every new launch might be wise to do.
Servers are expensive. You don't want to spec for peak load or you'll be bleeding money, SIGNIFICANT money, at normal load. To handle peak load, rent server space. It's out there, LOADS of it, and you can afford it. The goodwill and astonishment a successful, non-bogged launch provides alone is worth it, not to mention the money you saved on not speccing for peak load.
But there's complaining and there's complaining. Blizz not providing the service we paid for is completely and totally complain-worthy, but the decision to make the game always-online removes a much larger amount of complexity from the system as a whole than most people realize. On the sadder yet unfortunately still relevant other side of the argument, it hits a lot of money-words for the people who put dollar signs on everything, and having those people nervous makes very bad work environments happen for the creative people.
Tl;dr: I don't mind always-on requirement, but I require that the service be available for me.
I'd like to bring up another point that MAY have been mentioned in the thread already: I fear for the future of this generation of games. I mean, I love blowing the dust off an old console and play one of my good old games that I used to love. Sometimes the nostalgia trip dies horribly, but often I have a grand time. THIS generation of games will in large part not be playable in 10-15 years, because servers the game hits up in order to play will no longer be around. SOME companies might free their games from these restrictions, but many will not. I recently played Duke Nukem 3D again, and it was a fun time to frag a friend for a while. I also remember playing Bad Company 2, I think it was... can you multiplay that at all anymore? If you still can... sooner or later you won't be able to. The game, with whatever good and bad it ever offered, is essentially dead forever. At the very least the upgrade systems and shit will no longer apply, as no server records your progress and gives you new toys. Will this generation's games, at least a fairly large part of them, be lost to the ages?