UPDATE: Wednesday 03.06.2013 (07:00 EST/06:00 CST/04:00 PST)
Over the next few hours, we'll be deploying a server update which should help to improve game performance and resolve the following issues:
Trading not working consistently
Unable to load/claim city errors
Getting stuck in a loop in the tutorial
While this update is being applied, you may experience intermittent performance issues, which we apologize for. We'll provide more information on the update process as it becomes available. We also recommend keeping an eye on this Answer HQ thread for further developments.
The SimCity servers are currently inundated with the masses of eager mayors attempting to govern their cities.
Some players may currently be experiencing issues or delays when attempting to join a game server or region - or may be unable to create a city at this time. Additionally, there are intermittent reports of friends list, invite, and tutorial delays and errors. We are working to clear traffic from the roads and hope to have all players managing their cities as soon as possible.
We're sorry for any inconvenience this may cause and appreciate your patience while we work on a resolution to this issue.