Hotel chain Best Price Guarantees are for the most part Best Price Gimmicks, there are so many holes and exclusions that it serves to say that the chain has the best price without having to have the best price.
However you don’t earn points, stay credits, and you’re not supposed to receive elite recognition if you don’t “book direct.” Still if the price is good enough you can buy your won breakfast or even just book the room you’d like to stay in straight away, and still pocket a savings.