If you live in the US right now and own a Wii-U copy of ASRT, it’s not been the smoothest of experiences.
However for people living in the EU, it seems that we may never experience the same problems that US owners are currently facing. The update currently available for EU owners of ASRT doesn’t cause the problems that US owners are currently facing.
Executive producer Steve Lycett posted on our forums to assure EU users that
EU update is fine and is the same as the one that should hit the US anytime now.
Worth getting as it does make some improvements and tweaks the difficulty in places!
So there you have it, if you live in the EU and got a Wii-U today, patch away. As for you guys living in the US, the patch to fix the issues is currently in the hands of Nintendo awaiting release.
Stay tuned to TSS for more updates and our Wii-U review which will be up in the near future.
Source: Sonic Stadium Message Board.