Pros
Better than average pay, there is always someone to go to when you don't know the answer to a problem. Everyone is generally nice. Work environment is clean. Beats the hell out of fast food. If you happen to not have a college degree this is a place where you can move up, whether you start in sales or services. Also if you didnt have the chance to go to college provides an excellent tuition reimbursement program, $3500 for undergrad $5500 for grad school.
Kontras
It's retail. For geeksquad CIA's, customers are usually incompetent. If you don't feel like dealing with people work in stocking or as an autotech and generally you can get away without interacting with too many people. Also for CIA's I would recommend working in a standalone geeksquad store as apposed to the precincts within bestbuy.