TomThomson (9/29/2014)
I don't think I would call SQL Server mature. SQL Server 2000 lasted long enough to become mature. Maybe SQL 2005 did, I didn't have enough contact with it to find out. SQL Server 2008 didn't, SQL 2008R2 even less so - by the time SQL 2008 R2 was becoming mature it was no longer possible to buy it. SQL 2012 and SQL 2014 are still too new and have too many bugs/inconsistencies/irritating quirks - many of them with Connect items that have been closed "won't fix". There is no attempt at all to bring the behaviour of the data engine into line with the apparently clear semantics of T-SQL - there is a connect item still open, MS promised action years ago, nothing is happening - apparently because there is a lot of careless optimisation that prevents the engine from doing what the T-SQL clearly tells it to do and that is too hard to unravel.And as someone else said, the licensing is a nightmare - incomprehensible documentation, no-one willing to clarify it in any attributable manner. Being a nightmare is surely a sign of immaturity? Being incomprehensible and refusing to clarify certainly is.
The one thing I'd say, Tom, is that the core of SQL 2012/2014 is very mature. The bugs are mostly in changed areas. The things that are quirky, or you may not like, are mostly the same things that exist in 2005/2008/R2. They haven't been improved, but they work as expected, though not as designed.
As a core RDBMS, I still think SQL Server is mature. There are less things in 2014 that make it substantially better than 2005. A few, but not many, and it's not really a big change from 2012 for the requirements of many applications.