Well there are two distinct types of Apple customer service.
In the Apple store:
I'm not a big fan of going here when I need help, but sometimes it's a necessary evil. The sales staff is usually overworked. I HATE how I have to "check in" if I know what I want, especially with a big ticket purchase. I also hate how I have to hunt down an employee with a portable register (good in theory, not in practice) if I want to make a smaller purchase. ONE register open? Ridiculous! Also, I've noticed that if you approach an employee who's busy with a customer, they don't even acknowledge you (no eye contact, nada). I've worked in (computer) retail and it can be a pain to deal with customers, but we were always trained to at least acknowledge the customer's presence. Sometimes when I'm in the store, I'll look around and see a number of frustrated customers who need help. Many don't have patience, understandably, when it comes to giving a company their money.
As for the genius bar, it's really a mixed bag. I understand the need for reservations, but most stores are incapable of handling walk-in customers. Some genius bar employees are pretty happy to help out, but there are many who are a PITA to deal with.
Over the phone:
Every Apple employee I have dealt with over the phone has been very polite and courteous, and the vast majority of them have been knowledgable and able to help me out with my problems.