I don't know why other people like it; that's their issue. And honestly, I haven't paid any attention to the "hype", but then I live in the world of storage and file systems and don't worry about marketing chit-chat. I don't find ZFS particularly awesome, just a well-integrated package.
Why do I use it at home? Because there are a few features I want, or more accurately: insist on.
- RAID that is integrated with the file system: rebuilding unallocated space is not only a waste of time, it hurts performance, availability, and most importantly reliability.
- RAID that can work with uneven disk sizes, and that can therefore be used to upgrade to larger disks without downtime.
- On-disk checksums, because bit rot happens today.
- Scrubbing, because finding disk errors early helps reliability, and makes administration more relaxed: fix problems before they become a crisis. My system has ample spare throughput to allow for good scrubbing.
These features are hard to find in a single file system, until you go the high end, to some very complex (and often expensive) offerings, which often won't work for small systems and a small number of disks. To some extent one can piece these features together (for example by using a separate RAID layer and a file system on top, and then do checksum in user-space with a daemon), but having it in a single integrated package works better (see rebuilding of unallocated space argument above), and more importantly for me it makes administration easier.
There are lots of other features (ACLs, snapshots, quota, multiple file systems in a single pool, caches and ZIL, ...) in ZFS that I don't happen to use. I might start using them in the future, but my home server is simple enough, it hasn't needed them (yet?). I also continue to use UFS for the boot file system and system disk (which I do have partitioned into about a half dozen file systems, but I don't find the problem ShelLuser describes above to be trouble, YMMV).
Matter-of-fact, there are really only two reasons I switched from OpenBSD to FreeBSD: (a) better wireless drivers, and (b) ZFS. And reason (a) has become obsolete now that I don't use my home server as a wireless AP any longer.
Oh, and the most important feature of ZFS: Unlike some other file systems, it doesn't murder your wife.