We took the kids on one of these during our recent visit to Chicago. For five people, it was almost $200. But we figured it was an all day activity, and it would get us all over the city.
The bus itself isn't bad. You get headphones and narrators tell you about the town. But if the bus is crowded (or if the weather is bad) and you can't sit up top, you are going to miss a lot.
They run about every 30 minutes, so you will need to plan your schedule around it. We missed one, and the kids were bored for awhile in front of the Hancock Tower. And their app didn't seem to work in showing just where the buses were.
But we did get a nice scenic drive through the entire city. The drivers on all the buses were friendly as well.
I would recommend for a good sight seeing trip, but for how much you are paying, you probably want to get an early start on your day.