I just scored a Dell laser printer for $30 in a pre-black friday sale, so I really don't have any complaints. They were out online and it was a 20 min wait for customer support chat, but the nice lady checked stock at nearby stores and found 4 in stock at the Green Valley location.
I couldn't find it on the floor, but the employees were really friendly and helpful. Their inventory only showed 1 left in the back, so I'd call ahead even if online search shows that the store has it in stock.
I can't say how knowledgeable anyone is, since I walked in the door knowing exactly what I wanted. I thought they were great from a basic customer service stand point. And I like Staples in general, having dealt with them for my current and past companies. But we also spend over a million/year on office supplies, so they have a little more motivation to play nice.
Pricing is generally pretty high, but that's just how it is with office supplies. However they do have some great deals including online coupons and rebates - I've gotten free reams of paper with rebate coupons off their website.