Just saw a comment in another thread, stating Apple had slipped in improving their Unix layer, and here comes this. New file system is not a joking matter: Microsoft failed to deliver their new FS; Linux took years to go from ext2 to ext3 to ext4, and btrfs is in forever testing; most of *BSD still use their old ones; zfs took decade to become mainstream...
The information currently is very scarce on this one, but I hope they would at least test it REALLY WELL.
And Linux has the blessing/curse of having a million distros, each implementing their installer a little differently, exposing subtle bugs and inconsistencies in the FS/bootloader department.
And AFAIK, GNU Grub hasn't done a release in about four years now, and all the distros are using their own, custom beta build of it. It's a bit of a mess.
Many distros didn't support other file systems (JFS, XFS, et al back in the day) officially, but you could usually find a way to use them as boot or a forked installer.
I realize new file systems are difficult, but HFS+ is just an ancient mess that's needs to be replaced for a long while. This isn't new and innovative so much as finally getting around to removing technical debt and catching up with the rest of the world.
Windows and WinFS is a bad comparison. WinFS was just a tagging/metadata system on top of NTFS with a SQL storage backend. We're still quite far from the ability to tag files with custom meta data and have it easily to query using default file chooser dialogues.
The information currently is very scarce on this one, but I hope they would at least test it REALLY WELL.