The ol' Celtic Cross is a staple, so popular and ubiquitous that there is not very much left to say about it, really. I think many Tarot authors assume you will be familiar with it somehow, so there is no need to dwell on it.
I started out using it exclusively, and even now I use it for people who hare having their cards read for the first time, as it does give a good bird's-eye view of a situation. Like all positional spreads, it can be somewhat limiting, so I don't use it for myself, or for more specific questions. It is, however, a good enough spread nonetheless. It is one of two I know by heart, although right now I'm making my first serious steps into astrology in order to carry out the Opening of the Key.