I used Booking.com for booking hotels and shuttles from airport/train station to hotel in Europe, that I booked in advance from US prior to the trip.
No problems with booking (and cancelling) hotels and experience was good.
Booking shuttles was OK. Prices were probably on the higher end, but 2 out of 3 trips were successful while 1 failed at picking us up at the airport on arrival. Being in the middle of a transit strike might have affected it. Within a few days of trip, booked with two places, and both immediately sent mail rejecting reservation. Third place did not reject us so I assumed we were good. We were delayed getting off plane so I called them to advise to wait for us. They said "what reservation?". So I had to contact a new place which I easily did with help of airline rep in baggage claim.
