Pros
You do get an opportunity to learn quite a bit about doing repairs to hardware as well as removing viruses but most of that is quite basic. All challenging problems get sent out to the service center. You can also get tons of experience working with irritated customers as sadly they come in irritated far more often than not. The pace of work is usually pretty fast and challenging when there's customers coming in and you're trying to get to all of them at once so you're rarely bored. I can't think of anything else good to say about my job at Geek Squad.
Cons
Oh let me list the things! First of all, say goodbye to your social life because they never give you a consistent schedule. You never know your schedule more than a week ahead of time so it's impossible to make plans because you never know when you'll be off. Also from my experience the managers within Geek Squad are all horrible. My first manager got arrested for stealing from the store and now my next manager acts like a dictator of a country, he thinks he's encouraging but really he's just annoying all of us to death. Expect a bad manager. Also when you first start, don't expect more than 1 day of training even though their system and rules and such require a lot more learning than they think it does.