I've been using it the past 30 minutes or so and it's pretty good and very feature rich but I might stick with Liftoff for a while just because I got used to it. Some issues I had with Sync:
The default font size is tiny, I had to go looking in the options to increase it.
It seems like expanding replies of comments is a bit buggy. It seems deep replies are showing before the comments they're replying to.
The UI is pretty overwhelming at first. Feels like there are so many buttons and knobs that do a lot of things, a few of which are redundant. That's definitely just me not being used to it, but that's my first impression coming in from apps like Reddit is Fun which are fairly straightforward.