Apple's really low on the horror stories, but I still find their support frustrating, and would never place it near the top of my support experiences. The complete lack of email support, combined with having to make appointments on *their* time, which they may not even be able to fulfill, is really frustrating. It can also mean going weeks without support, where similar warranty plans from other companies mean you send off an email at lunch and you've got someone at your door the next day (not exaggerating, I've done it).
Their actual staff are often better trained, so after waiting an hour in line, at least you'll usually get good help, and I appreciate that, but the idea that apple's support time is more important than my life and job is part of the atmosphere I really dislike about the apple community. If I have to leave a dead computer at home for a week or two until there is an open appointment at the bar I can make (and god help you if it dies around the time of a product release - you may not be able to fit through the door), that's not good service to me.
Overall they have good support, particularly for a tech company, but for that reason alone I don't think they deserve to be marked the best. I can't think of an example from the larger computer makers, but this is about all businesses, and there are several other companies out there that will provide both quality service, and work around your schedule.
Also, if you've ever tried to run macs in a corporate world, Apple's concept of corporate/healthcare/government support is way, way out of skew with the industry. They don't have the right dedicated people or plans to provide the support these area really need in a timely manner. Maybe they just favor some companies over others, but my experience is that they place business relationships well down on the totem pole compared to other big PC makers, which makes this result from "BusinessWeek" of all places rather odd in my mind.
