The transfer at PEK has been consistently excellent for me - I have used it many times. I usually book through the hotel, combined with a pickup from the hotel. It usually involves two people - one guiding you from the jetway, through immigration, luggage, and outside to the car, and a second person driving the car to the hotel. Back, it works the same way, and you get guided up to the lounge. I highly recommend. It's not a priority service (they don't allow you to skip queues), but it's very convenient - and overall reasonably prived (compared to the CDG Concierge service, for example).