Things are progressing pretty normally. rc5 is smaller than rc4 was, and nothing looks particularly scary for this release window.
Let's hope it stays that way.
The diffstat looks normal too, with just over 40% driver updates, and just under 40% arch updates. Although the reason the arch updates show up that highly is actually largely a single MIPS BPF JIT file that had gotten lost (somebody forgot to "git add" it, methinks), and that got fix up here.
Outside of drivers and architecture, it's the usual random stuff: networking, core VM, header files and some scripting. And various misc one-liners.
Shortlog appended, you can get something of an idea of what's been going on from it - lots of small details being fixed up.
Go forth and test, and everything says that we'll get 4.13 out in our usual timely manner.