I have had two negative experiences.
A while back, a Powerbook trackpad failed while still under service contract and Apple didn’t want to fix it because the service person claimed something was spilled on it. Though the machine was used by other family members, I know of no actual spill. They wanted something like $900 to repair it. I ended up getting an aftermarket trackpad off of ebay and fixing it myself for $40. So much for the extended warentee. I must admit that a service manager called me after I sent negative response to their after service questionnaire. He offered to have another look at it, but by then, I decided I could handle it, myself.
My iMac hard drive was recently recalled due to a high failure rate. I made an appointment and took it in to their store. Result – after waiting around for a while, someone checked out my machine and made sure that it operatated correctly, found that they had the replacement drive in stock, then said that they would have it ready in 3 to 5 days. I asked if they were going to migrate the data. The answer was no, it was going to take so long because changing hard-drives was a “delicate” operation. 5 days to change a hard drive, without migrating data – Apple, give me a break – you can do better than that.
While waiting for help on the iMac hard drive, a woman came in complaining about intermittent WI-FI connectivity with her iPhone. I can’t imagine the Apple “genius” solving that problem.