Microsoft has released Service Pack 1 for SQL Server 2014. However, do not install it if you use the SSIS catalog (SSISDB). From the Release Services team blog:
And you can see what can go wrong in the comments on this Data Platform blog post. If you're not using SSIS catalog / SSISDB, you should be fine, but if you haven't already downloaded the file, it's been removed – so you are going to have to wait for an updated package anyway. If you have already installed Service Pack 1 and SQL Server couldn't start, please see this post for a fix.
For now, it is build 12.0.4050, and contains all fixes up to and including Cumulative Update #5 (12.0.2456). In addition to staying away if you use SSISDB, DO NOT install SP1 if you are relying on fixes from Cumulative Update #6 or any COD updates that came out after CU #5. Relevant links: