"Curious how many people who run Fedora would actually plump for anything other than ext4?"
Quite a lot. I mean, Fedora's meant to be an experimental, bleeding-edge sort of a distro. If you're the kind of person who wants to play with btrfs, the chances you're running Fedora are quite high.
The review gives something of a misleading impression of Fedora's btrfs support, although it's not _wrong_ exactly. The key thing it misses is that btrfs support actually regressed in 17, which is unfortunate but somewhat unavoidable.
From, oh, 11 or something like that through to 16, we've had support for btrfs in the installer. (For several of those releases you had to pass a sekrit parameter on boot to prove you were smart enough to read the documentation and so with any luck smart enough to know that btrfs was likely to eat your data and your babies for dessert, but the support was always _there_). However, btrfs was treated more or less as a dumb filesystem like ext*; there was no account taken of its advanced features like volume management or mirroring.
There's a new anaconda UI in the works, and it was initially planned to land in F17. So someone went ahead and rewrote the btrfs support _backend_ in anaconda to be much smarter and support all btrfs' advanced features. The frontend in the old UI code was not updated for these changes, because the idea was the new UI would be arriving anyway.
unfortunately the new UI, er, didn't arrive, it was clearly not going to be done in time for F17 so it got postponed to F18. This meant we were stuck with some smart new backend code but no matching frontend code (the mix is explosive, you just get a crash). It seemed something of a waste to devote considerable resources to extensively updating the old storage UI for a single release, and rolling back to the old backend code wasn't really very easy to do either, so in the end we plumped for just temporarily disabling btrfs support in the interactive installer for F17 as the easiest option. It will return with the new anaconda UI in 18.