I never book hotels without a quick look at TripAdvisor.
This site covers hotels worldwide from well informed travelers, plus you can compare room prices while looking at reviews.
Having stayed at hotels throughout Europe I find most of the ratings to be pretty much spot on for accuracy and the bonus of finding hotels you would not find otherwise is fantastic.
For worldwide hotel reviews TripAdvisor is a must see.
Only just starting using Hotwire this year and had great results each time.
If you are adventurous and willing to take a chance on what hotel you get, you pick the city, star rating, area and price, you are given a selection to choose from of which you book & pay in advance, only then do they reveal the hotel name.
I booked several business trips to Toronto and have had fantastic results at 4 & 5 star hotels for about 3 star prices, beautiful hotels in the area I needed to be. Super.. Hotwire is fantastic for last minute bookings too.