Ive read plenty of threads of problems with the time capsule, particularly the 2008-ish models. Some of it seems to be specific manufacturing defects (dodgy capacitors), others about the inherent nature of having an hdd, router & power supply in a non-vented enclosure.
With regards to the latest generation, what are your thoughts? Are you happy with yours? How much do you trust it for your backups (c.f. a standard external usb hdd)?