In response to Philzone. Im not saying Smoke on the Water is the best rock intro, instead I think it is in the category of "best intro that leads to a disappointing song" i.e. blues-rock-by-numbers growling. One of those tunes that seems to have invented just for the purpose of sampling. How many times has the opening been used on soundtracks, commercials, title sequences only for the vocals to be faded out?
[Pere Lebrun had a pithy description of the song on twitter, but I can't find it now.]