A few of the customer-requested updates in Microsoft SQL Server 2014 SP1 are:

• Column store performance is improved when batch mode operators spill over to disk. A new XEvent provides insights into column store inserts.
• Several issues in buffer pool extension SSD configuration are addressed, including the ability to do instant initialization of the buffer pool extension file.
• Certain queries compile faster when using new cardinality estimator, and other cardinality estimation query plans are more efficient when using TF-4199. 
• The scalability benefits of two trace flags (TF-1236, TF-9024) are applied automatically.
• Backup header information retrieval works better with encrypted backups.