We decided to wait for VS2015 because 2010 was fine and we didn't find 2013 had enough to offer in terms of improvement for our dev team.
That actually surprises me a bit. For my team, VS2012 (and later, VS2013) were night-and-day performance improvements over VS2010.
I have been using VS2015 throughout the betas with mixed results, but the latest RC was OK, so I put RTM on my main dev machine. There have definitely been some hiccups - it takes longer to load our main product's solution, and it hasn't been as stable as VS2013 was. However, I have stuck with it because Roslyn and its integration with the IDE is a leap forward compared to the tooling in VS2013, especially when you start looking into analyzers. Such is the price of living on the edge, I suppose.