This depends completely upon your drinking tendencies. I drink exclusively water, and so it provides no benefit to me whatsoever. My 3 girls only drink water and milk, and we dont eat breakfast in the food court, so again, no benefit. DH drinks soda and is willing to make the run to the food court to fill his once we get the girls to bed after the parks at night, so for him it saves the cost of one drink per day.
However, if you tend to spend the afternoons in the hotel pool or eat breakfast in the food court in the mornings or even if you tend to return to the hotel earlier than we do at night, you might get a couple of drinks worth out of them per day, if soda is your thing. My mom likes hers because she can take a soda into the parks with her each morning. The frustrating thing about them is that they arent water tight. If you tilt them or put them in a stroller cupholder, they WILL spill. Because of this, we dont use ours for water in the parks either, we use our Camelbak bottles because they can get tossed into the backpacks or sit in the cupholder of our stroller without making a mess.
The long and the short of it is, it depends. It depends on your touring style, it depends on the beverages you prefer and it depends on what you want to use the mug for. For us, they sit unused in our room most of the trip, but for my mom they're indispensable.