SimCity server upgrades are now complete, with all original servers successfully migrated to "new, faster/higher capacity server architecture," live operations producer Barrie Tingle confirmed on an updates post on the official SimCity website.
A server status page can now be viewed here, with information regarding all available servers for the game.
In addition, patch 1.5 was deployed yesterday to address trade intermittency issues, which aims to help make regional interaction more responsive. The team plans to offer continued improvements to the speed between cities within a region. This should decrease the chance of losing progress on your city through rollbacks. You can view the full patch notes here.