It's certainly interesting, but if you look at the ZFS design they were inspired by, they got a lot wrong. Some points to consider:
With ZFS, you have a hierarchy of datasets. These inherit properties from their parents, and while the mountpoints can also mimic this hierarchy, the mountpoint property can be set independently. Btrfs couples the two concepts, forcing subvolumes to be in a specific place in the actual filesystem; zfs datasets in comparison are purely metadata and are for organisation and administration, not direct use in the filesystem hierarchy.
ZFS snapshots are read-only, and clones of these snapshots are datasets in the hierarchy. Btrfs snapshots are read-write by default, which in some ways defeats the point of a point-in-time snapshot. You can also make changes to a ZFS clone and later promote it to replace the original dataset. Likewise rollbacks. Btrfs makes no provision for doing either; you have to delete the original and then rename the snapshot, which isn't atomic. ZFS' metadata preserves all relations between datasets, snapshots and clones.
The ZFS way of doing things makes things safe and accessible for system administration. There's no way to confuse the origin of a snapshot because it's tied to a parent dataset. Likewise clones of snapshots, unless you deliberately choose to break the link. The Btrfs way looks superficially nicer, but in practice is much less flexible, and potentially more dangerous since you don't have the ability to audit what came from where and when. Btrfs snapshot performance is also abysmal. ZFS handles snapshots simply by recording the transaction ID, which makes them really lightweight (and it also provides "bookmarks" which are even lighter weight). ZFS keeps the referenced blocks in deadlists, and its performance is excellent (compare how fast snapshot deletion is between the two). ZFS also allows delegating permissions to perform snapshot, clone, rollback etc. to normal users; I'm unware of Btrfs allowing such delegation--some operations can be performed like snapshotting, but not deletion, while ZFS permits this all to be configured transparently.