Time bloody Machine
When it works it is great. And most of the time, it just works.
When it fails - well there's not much you can do to find out what's gone wrong. There are no detailed error messages and no obvious way of looking at the processes - the new backup reports in the Console are unfathomable.
Apple's advice for when things go wrong beyond turning it off and on again, quickly goes to 'erase your backup disk and start again' then to 'you need a new Time Capsule'.