Ea are still experiencing some major issues with the Sim City servers and yesterday they announced on the official forums that some functionality would be temporarilly suspended to improve stability.
"We are continuing to do everything we can to address the server issues. In the meantime, so that we can give you as good an experience as possible, we are in the process of deploying a hotfix to all servers. This includes various improvements and also disables a few non-critical gameplay features (leaderboards, achievements and region filters). Disabling these features will in no way affect your core gameplay experience.
We will continue to let you know as we have more information. We know it has been said before, but we do appreciate your patience as we complete this latest update. Getting you playing is our absolute highest priority."
And now Amazon have decided to stop selling the digital version of the game as customers have voiced their dissatisfaction.
"Many customers are having issues connecting to the "SimCity" servers. EA is actively working to resolve these issues, but at this time we do not know when the issue will be fixed."
It's going to be interesting to see the sales numbers of Sim City to gage whether this was a case of unexpected demand or if EA simply didn't have the infrastructure prepared in time.