Having worked for Apple for a little over 5 years, I can tell you it's a good job. Pay isn't the highest, but it's better than most retail jobs. Benefits related to health and dental are where the good stuff is though... both part time and full time employees enjoy comprehensive benefits (and at very minimal cost per pay-cheque).
Environment is good, busy. People can be very demanding and self-righteous... very demanding as if they are the most important person alive. You get the usual yelling people, you get sad people, you get every type of person you can think of.
Advancement is okay if you sip the sauce... peers are very competitive, and there can often be a sense of favouritism. So be prepared to play the political field with your peers and managers.
Good luck working a second job, or getting two consecutive days off.