Pros: comprehensive selection in many cities, easy search, excellent prices in many cases, ability to scope a particular property's amenities prior to booking (unlike Priceline, etc.), never a problem getting reservations honored or being treated like a second-class guest.

Cons: not always the lowest price or even a GOOD price, inability to book more than one room at a time on the website (making it difficult to use for group business trips), you have to prepay entire cost of room at time of booking (as with Priceline), bookings don't always earn points with some hotel chains' loyalty programs (as with Priceline).