Hey, that's great!
The problems I hear about Wuala and syncing is when people try to e.g. edit Excel sheets on different computers at the same time and expect Wuala to sort it all out for them.. that's a common one, for some reason. Go figure.
Another more serious issue is one which I think is fixed in the latest version (and NB: it auto-upgrades itself all the time, good to be aware of), but I'm not certain because I don't use the Windows version very much: The CPU usage could go up to 100% on computers with intermittent network connectivity because if it tried to sync when disconnected from the net. And possibly also in some circumstances related to sleep mode.
I haven't had any issues at all the way I use the software. I dump files into Wuala on my desktop, for example, and looks them up on my Android tablet (over wi-fi) at home. And when on holidays I dump pictures from my camera into Wuala from the hotel room - more in the past though, with smaller SD cards (I guess you can tell from that that I have more than the 5GB free storage space). It's great to know that everything is encrypted pre-uploading.
Just today (the last few hours) there's been some network problems at their servers though so access hasn't been working all the time. That's the first time I have been affected by that, although it's happened before - but not for so long.
http://status.wuala.com/-Tor