We haven't experienced any bugs so long as we both keep our versions in sync. Once one has a later version than the other, all bets are off. That's a problem that's tricky to solve correctly though.
Aside from that, we were disappointed by the constant needs to restart SyncThing when saving configuration changes, some lack of UX features (e.g. being able to move where your sync share is stored -- I made an issue on Github and was told to edit the config file manually and restart SyncThing -- I asked if a pull request would be accepted if I added the feature myself, and got a vague response.)
Overall though, SyncThing has worked excellently for us.
I was trying to sync seven machines in three different physical locations, some with slow internet connectivity; only one machine in each location had its syncthing ports open to the internet through NAT. I'm not sure it's a supported use case: syncing in the same LAN generally worked fine, but changes often didn't propagate correctly to other locations; for instance a folder name change sometimes was not propagated to the remote locations, and after some time the machine in which the rename had happened detected that the rest of the machines in the syncthing group had a folder which didn't exist locally (the folder with the old name), and downloaded it from its peers. The result was that the folder was duplicated everywhere, with both the old and the new name.
The same happened sometimes with deletions: sometimes they didn't propagate over LAN boundaries, and this resulted in the deleted files reappearing after some time.
A machine staying "syncing..." forever also happened sometimes, requiring a manual restart of the service. I couldn't reliably reproduce it though.
I like the project and I'm sure if I reported the issues in github they'd have given support. I wish I had the time for properly reporting and investigating, but I really needed a syncing solution I could trust for a small business and I needed it ASAP, so I settled for owncloud (which for the moment has not given me any surprises). I will try to find some time to reproduce the bugs in my personal machines and report them, but I really didn't have the time when I found them.
[1] Okay, this is true for BitTorrent Sync versions < 1.4 -- more recent versions have been less reliable, particularly with regards to cross-platform syncing.
maybe the active spideroak project with nimbus is something for you
https://github.com/SpiderOak https://github.com/SpiderOak/nimbus.io
I think it's just that the software is not yet mature and production-ready, and perhaps I was throwing too much data at it at once. Seeing the project progress, I'm confident that when it becomes more stable it will be a very nice piece of software, but it's not there yet.