Made an appointment online for the Genius Bar, arrived early, and got prompt service. I wouldn't show up without an appointment on the weekends, as they seem to be slammed all day. The diagnosis on my hard drive was not a complete disaster, and I got my laptop back in less than 24 hours. Even if it would have been a disaster, that's what backups are for. Informative, helpful staff, but don't show up on the weekends and expect to walk in for repairs and be first in line.