The release notes state that there is basic F3 support in the Windows 10 edition only. However, pressing F3 does absolutely nothing. I have tried with both a current world and generating a new world with the same results.
Addition by @unknown:
It looks like the mentioned F3 support won't be included in this update. Here's the statement from Mojang:
UPDATE: this list originally included entries for F3 support and coordinates, but these didn’t make it into this release after all. Soz.
Can confirm... even enabling cheats doesn't work.