We typically jump on one of these when visiting a new place, as they are a good way to see the city.
This one is fairly short - 75mins they say to do a circuit, which we did, Plenty to look at and we opted for the 4 hour ticket, as this is often enough to do hte full tour and get back to a place you want to explore, which we did.
At this time of year, it is around 40degrees centigrade, >100degrees FH. Bl**dy hot!
We opted to stay down stairs and be in the Aircon. The bus has the usual free wifi (I think) and bizarrely DVD's running whilst on the tour - not of the city, but we saw a good dose of Desierto, which had plenty of shoot em dead, kill em stuff going on, graphic head shots and a dog mauling someone to death..... Not the best for 10 and 13yo girls!
Still, I would recommend doing a round....