I have 64-bit Windows 8.1 with all the latest upgrades (downloaded from MSDN last week). I have had SQL Express 2012 With Advanced Services installed for a long time and all working correctly.
When I do an in-place upgrade to SQL Express 2014 with Advanced Services (RTM), it doesn't do the upgrade; it just disables and stops the Browser Service so I can't connect with SSMS. When I restart the Browser Service, I can connect again but the splash screen shows SQL 2012 and when I am connected, the version is 11.0.3128.
I subsequently tried a Repair option but this didn't achieve anything and there were no errors in the log file. If you can remind me where to find it, I can post it here.