BI SPS15 --> SPS18 upgrade benefits?

Hi,

We are currently on BI SPS15, not using BI-A (yet).

We are considering an upgrade to SPS18. We do not have flexiblity within our schedule to wait until the GA of Enhancement Pack 1, thus the following question:

Are there any release notes or additional information in SAP notes (or elsewhere) that outline the fixes / benefits that come with an upgrade from SPS15 to SPS18? Are there any enhancements? or is it merely bug fixes?

I can't find anything in the help files, nor in SDN or SAP notes.

Thx in advance,