I've read some reviews which say that this tour is boring. If you are not interested in the history of Prague, or what the buildings are that you can see as you wander about the city, then it would be boring....but then what are you doing in Prague? If you are in a stag/hen weekend and couldn't care less about the culture of this capital then don't bother with this trip. Yes, the sailor suits of the guides are a bit corny. But, we found that if you expressed an interest in the city that you're visiting the guide on out boat was quite happy to expand upon the taped commentary and provide information that I was interested in.
Yes, some of the seating was a bit cramped. We didn't like the benches we had on the boat that we were put on at first, which was supposed to be the English and French speaking one. We got off and got on the next one, which proved to have an English and French commentary as well. There was no gluhwein as advertised, but we got two plastic cups of beer each. We were happy enough with this, but I would have preferred the gluhwein.
The gingerbread was ok, but we weren't really on the trip for the refreshments.
The boat doesn't go very far. It takes you to the weir, then across to the other side of the river where the water mill is, then upstream a bit. You get to see the Charles Bridge from the river, and the buildings in the vicinity. The guide answered all of our questions, as I said he seemed to be pleased that we were interested in his home city.
You get admission to the Charles Bridge museum for the price of your tour. We did find this interesting.
In conclusion, if you are a Philistine then this tour is not for you. Show an interest, then you my find it rewarding.