Paid $35 for 7 days parking including taxes and fees through way.com over the New Years holiday to ensure I had a spot (although I think you can save yourself the service fee of about 3,4 bucks if you pay them directly when you pick up). With no traffic, at all, it takes 12 min to and from the airport. Give yourself more time because sometimes they wait for others to arrive before departing. In my personal experience, sometimes it takes that long for the airport bus to pick you up from the extended lot.
Drop off was simple, you answer a few questions at the front desk then get on the shuttle. DO NOT LOSE THE TICKET THEY GIVE YOU- you need that number so they can retrieve your car. I took a photo of it.
Pick up was easy (because the driver was already on his way for someone else before I called) but it shouldn't be more than 15 min wait anyways. They take this time to get your car. If you prepay, then you arrive to the lot and your car will be turned on and ready to drive right off the lot. If you need to pay, you get off the bus, pay inside and then get to your car which is also on and ready to go. Pretty easy. I prefer to prepay so that I don't have to wait in lines or move too much with luggage. All in all, good experience and much cheaper than parking at the airport's extended lot.