Setting up new iPhone 6 issues and major headaches Old iPhone 5 16Gb all backed up on iCloud. Tried to set up my brand new iPhone 6 but turned out the last (manual) backup attempted on the 5 hadn't fully completed. Reinitiated a new mail backup on my old 5 to iCloud (18 mins), just attempted to set up new 6 using iCloud but get "error connecting to iCloud". Reset new 6, finally logged into my Apple account but showing zero available iCloud backups with which to restore new 6.

Over an hour and I still cannot even use my new 6!  Currently getting out windows laptop to do it all again manually via iTunes. Just feel like taking the 6 back to the shop. 

What can I do to ensure a good restore?
iCloud syncing over iPhones of different generations can be tricky. I highly recommend backing up your iPhone 5 directly to your computer (not iCloud) and then syncing that back up file to your new iPhone 6.

Once all the old data is on your iPhone 6 you can then sync it to iCloud through your iPhone 6 (which can be done in the background).

Hope this helps.