I used booking.com a lot.. in many countries.. and I have never had a problem.. I do check hotel websites and if price is better I usually book direct.. however I do like using booking.com if booking an involved trip with many hotels as it is nice having all my hotel itinerary in one place..

I always read the fine print.. and rarely book non refundable rates.. ( have an upcoming trip to England, Paris and Spain in july.. and only booked one night non refundable. .it was the last night at an airport hotel and I am pretty sure I wont be changing that.. )

I do book months in advance and have cancelled and rebooked hotels many times.. never had an issue.