SimCity's problems were much like Diablo 3's character creation problems at launch.
With Diablo you had a hell of a time just getting a connection to a server - but once you were in you got to play (laggy though it may be).
With SimCity you'd bash your head against your computer connecting to a server, but even after you do that every step could possibly fail because it was doing something substantial to an internal database (presumably) that doesn't scale - creating a city, taking over a city, joining a region, etc etc.
See even once you're past the dreaded "wait 30 minutes for your turn", there's still no guarantee your game will even be functional.