my only complaint with amazon is their increasing usage of USPS-based fulfillment
I'd be perfectly OK with it if they hadn't increased the minimum order from 25 to 35 to qualify for free shipping.
I've got a good mail carrier and the actual post office is only a few blocks away. On the other hand, I've had issues with UPS and FedEx in the past, but I'm sure everyone out there has a similar story about X carrier.
I use Amazon a lot for little things here and there that I don't need immediately, but I'll admit that it's sometimes a struggle to tack on an extra 10 bucks of stuff when I'm not really in need of anything else specific, but I'd rather spend 10 bucks on an item than spend 7 bucks on shipping.