Starting with 3.6.0, and continuing with all the 3.6.x subsequent releases, I've noticed a power regression on my ThinkPad X1 (Sandy Bridge, Intel HD 3000 graphics). The rc6 power mode of the GPU fails to engage, thus the GPU runs at 100% and cranks the temperature so high that the fan kicks on full blast. There's a fairly long forum thread at Arch about this, although I'm noticing it with every Ubuntu mainline build. Curiously, I don't experience this problem on my T520 with nVidia graphics (Nouveau driver).
Now with the 3.7 builds, direct UEFI booting seems to be broken. The machine will start to boot, and then freeze after about 1.5 seconds. Nothing in the scrolling text indicates what the problem is. Sigh. Am I stuck on 3.5 forever?