Wuala is hardly better than Dropbox and it's not even getting close to Ubuntu One for that matter..
Depends how much you value your privacy. I don't know about Ubuntu One, but Dropbox technically has access to all the files you upload to them, while Wuala encrypts them on your PC so they can't read what you store on their servers. And you can't pay for storage with BTC @ Dropbox
It's a bit hard to find though, so here it is:
http://wuala.com/en/bitcoin