SQL Server 2008 R2 is released and have been a stable product since the day it is released. I have not received any complains or rants from any of my customers who has upgraded to this version. The number one request is how one can learn about the new features of SQL Server or how one can get going in using SQL Server 2008. Microsoft has released SQL Server 2008 R2 Developers Training Kit. This is awesome kit and I just suggest to have a look at the content one time.