Initially, things worked pretty well with some hiccups along the way which isn't too surprising for a 1.x product.
However, the straw that broke the camel's back was starting with version 2, BitTorrent decided to start making certain features premium. While it's entirely within BitTorrent's right to do so, they chose to do it in a way that legacy installs of various vintage across multiple machines would break in a fashion that would require a reinstall. And lo and behold, a reinstall causes further breakage.
So if one wants to see how not to incrementally update (notice I do not say improve) a product over time, look no further that BTSync.
Even worse, recently I discovered that I actually suffered from data loss due to some strange idiosyncrasy of their sync algorithm.
That said, I'm now looking for suggestions for a product that I could use to synchronize across Windows and Mac for both 1Password and regular files.