Good enough for a minor overclock even. I have a 6700K and a hyper 212 evo and have gone as high as 4.5Ghz no problem (all core stock is 4Ghz or 4.2 with MCE enabled). I've used the 212 in 2 builds now, but I'll be looking for something a little better next time. There are a lot of options around these days.
Even a $20 cooler can handle stock speeds. Almost anything is better than intel stock coolers, not that the 7700K comes with one though, and they still manage to do the job more or less.