I did not buy the official cover, but a cheap top/bottom (but not side) acrylic case that included a fan, and also applied 3 heat sinks which came in the basic kit that came with the pi from canakit. It idles at 47°C and can browse "new reddit" at 59°C. A samba share its hosting causes it to run at 59°C during file transfers to an external SATA drive connected to the USB 3 port. I'm pretty happy with it considering all the complaints about heat issues. Only issue I've had so far is that you cannot reliably power more than one external hard drive with this. A second one will need its own power adapter.

There was a firmware update, so make sure you applied that. Might help bring the temps down a bit.