The UI, which was the vocal point in my Play Store review is getting better in each update. However, if looking at a function-over-form perspective, the app is admittedly, very usable.
Apart from the lack of Mac and Linux client (requiring me to use a Windows machine to cross-transfer to my PC), I don't see much to complain about and the solid transfer performance is something I appreciate a lot.
Overall, would definitely recommend. I plan to use the app as an 'on-the-go' replacement for Samba, and it seems to be to doing that job well.