As usual, post-RC1 the changes in this week's kernel upgrade are all about bug/regression fixes. However, as another not too surprising attribute, Linus is starting to get angry over large Git pull requests late into the kernel cycle. Linus explained in the announcement, "[this release is] already big enough...I'll start shouting at people for sending me stuff that isn't appropriate as we're starting to get later into the release candidates."
The Linux 3.13-rc3 release doesn't have any major noteworthy fixes but just a lot of changes scattered throughout, mostly to Linux kernel drivers and file-system / architecture updates. The Linux 3.13-rc3 announcement can be read on the Linux kernel mailing list. For the major features forthcoming with Linux 3.13, read 13 reasons Linux 3.13 is going to be very exciting. More Linux 3.13 benchmarks are forthcoming on top of the benchmarks I've already been running with this major kernel that will be stabilized around January.