I didn't use any cloud storage service before, mostly because of security. I usually don't really care about my data being that attractive to big companies, but didn't feel well to have all my data stored in some unknown sky. Finally I tried Ubuntu One for one file not being worth to be stolen today.
Usage on Ubuntu is very easy: Run Ubuntu One from the launcher, fill in name, email and a password (oops: Why do they require upper and lower case chars?) and finally check your mailbox for a verification code.
There is a precreated "Ubunut One" folder and bookmark in Nautilus (the Gnome/Ubuntu file manager) and I moved my 40kB file-to-sync there. A bubble popup told me that the file is being uploaded to Ubuntu One, but it didn't appear on the website, even after waiting a few minutes (and refreshing the website multiple times).
File sync is (nearly) useless for a single computer and I started that U1 approach for syncing between Android and Linux. There is a Ubuntu One App in the Android Market which should sync the Ubuntu One files with your Android device... yes, it should, but it doesn't.
It may auto-upload your photos to Ubuntu One but for everything already stored within the cloud - it's just a simple file browser. The app is able to download ("prefetch") the file list itself, but the files are downloaded on demand only - pretty much the same thing Google Documents does.
Why does Google think that every Android device always has a high speed connection to the Internet? Google Maps is useless without network connection and the GMail app also lacks a good offline support. Ok, Google might be wrong, but why do so many developers of Android apps do the same mistake? The Ubuntu One app is useless for me, because I very rarely take photos using my tablet and most of them are not intended for long-term-storage. I want my cloud files to be easily and always accessible, even within badly GSM/3G-covered areas.
The app did find my uploaded file - but it was 0 bytes long. I re-uploaded it using the Ubuntu One website and finally the size was correct. A second file was uploaded automatically after copying it to my local Ubuntu One folder (on the PC).
FolderSync Lite is now able to use remote SFTP servers for syncing (besides other protocols). I'll try set up one over the weekend and use some rsync/unison/mirror tool for Ubuntu and FolderSync for Android. Maybe I'll even buy the full version of FolderSync which is less than €2.