btrfs is quickly becoming the defacto Linux file system and all major OSes include support for it (even DO's Droplets that don't allow using btrfs on root include the tools): CentOS, Ubuntu and CoreOS to name a few...
My main draw to BTRFS is the improved data integrity and bitrot protection provided by its checksums of data and metadata. Additional features of use in DO's environment are snapshots and pooling (among others).
I would also argue that btrfs on Linux is a needed option just as ZFS on FreeBSD is--in DO, one can choose UFS- or ZFS-based FreeBSD Droplets.
Links to additional information about BTRFS:
* https://coreos.com/blog/new-filesystem-btrfs-cloud-config.html - CoreOS has included support for btrfs for nearly 3 years now!