Hey Hodgey,
I work in the film and television industry and GoPros have revolutionised the world of rigging mini cameras for fx shots and we use them every week
They get great results but are finicky. If you want to use it primarily as a stills camera i would not recommend it over a dedicated stills camera. Firstly the gopro has a fixed lens which is very wide angle approx 120 degrees. Secondly, the Gopro out of the box does not have any sort of screen to review shots taken on the run. You can buy a screen but it is an add on and does not fit into the waterproof housing.
Another thing about the Gopros is that if you are using them for underwater work, you must make sure to get a flat faced housing not the original round one. the round one does not focus underwater very well at anything further than about 2 feet.
They are awesome little cameras but not as easy to use as digital stills cameras. They are best suited to HD video recording applications.
Hope this helps,
sam