The key part of Torvalds' release announcement comes down to: "The ShortLog is appended, but it's basically 85% drivers, with over half the patch being to the aforementioned new wireless one and the OMAP drm changes. There's some other stuff there too, but it's largely in the noise - small ARM and s390 updates (and a smattering of SuperH and x86), a few tiny filesystem fixes, things like that. Go forth and test. My gut feel is that things really are calming down. And I'd hate to be proven wrong."
For those not familiar with all of the changes being packed by the Linux 3.8 kernel, read the feature overview of Linux 3.8. There's a lot of great stuff!