I had one positive and one negative experience with them.

The good: they fixed my iBook when the logic board needed replacing, and got it covered under Apple's replacement program (it was a known issue with that model).

The bad: I took my external hard drive to them when it crashed and took my data with it. When they couldn't get it to mount, they reformatted it without asking me, which is pretty much the stupidest thing to do in that situation. It meant that specialist data recovery experts didn't stand a chance at recovering the lost info.

So yeah. They're Mac experts, but make sure they check in with you before doing anything major.