Diablo 3's release was horrendous, but it only lasted maybe a few days at most. I don't even own this game and I heard of all the issues with SimCity from my buddies at work. All I can say is that I agree with JC that this is the worst game launch in history. Diablo 3 might be up there because of it's popularity among gamers, and it affected more people, but at least Blizz fixed the main issue right away.
Valen you do have a point, but I think you're also adding in the fact that Diablo 3 bombed after the first couple months it was out. Most of that was due to progressive patch releases that had features that were promised when the game was released, like PvP.
The auction house destroyed that game, but it wasn't a glitch as much as it was just features like the real-money AH that were promised but not released right away. On top of the over-priced items and low drop rates.
SimCity on the other hand flat out doesn't work...which is way worse than Diablo 3's release.