There are only certain things that are backed up to Skydrive.

1. Contacts
2. SMS
3. Photos (if they are enabled in the settings)
That's about it. Everything else is NOT BACKED UP. So if you are playing those nice games, the game saves or any of the app data are not saved, whatsapp chat history are not saved (though the latest version of whatsapp have a backup function, no idea where it is backed up to though).

Even your grid layout is not saved so if you have those nice layout that you have painstakingly setup, you have to do all over again should anything happened to your phone.

I keep ranting that MS needs something like iTunes where you are allowed to save a FULL BACKUP of your iOS devices on the computer. They need to put this as the no 1 priority ....

Nowadays flagship phone cycles down to 6 months from yearly, which kinda piss me off because phones get outdated too fast... Just like Samseng release S3 in mid year and Note 2 in year end, HTC has the One X and Butterfly...