We actually took the hop on hop off tour during the day, then this Open Top Night tour at night. Though a lot of the same thing on both tours, it really does depend on the tour guide you get. We had 3 different guides over all of the stops and different tours we took and by far our favourite was Lindsey. Super friendly, very knowledgeable and always keeping us all informed of what to expect at every aspect of the tour. We had her at the first half of the day time hop on Hop off, then she ended up being our guide for the nigh time one as well and boy were we glad to see her!
The tour itself is also a lot of fun and they drop you off for a while on Freemont to experience the nightlife here. Word of warning, not for kids. As per any big city, there are, shall we call them interesting characters throughout the area and they are very active at night. A lot of the entertainment is not kid friendly either, so wouldn't recommend for that but for adults, it was a great experience. Can't recommend more.