Pete,
You will indeed to able to hear it loud and clear and probably see most of the main stage. The river runs right up next to the site and there were boats their last year.
Tried to upload a photo of where it is but basically, the main stage is very near the leisure centre. The site then runs up the river towards cowes. This may be the last year that it is on this site so make the most of it! There is a rumor that it will move to a bigger site.
I'll be there with bells on so watch out for me crashing the stage