After briefly trying a number of other slideshows, found this to be the easiest and most intuitive to use. Really nice admin interface, quick and easy to add slides, and can drag and drop them around to reorder.
Custom css very well integrated and flexible. About the only nitpit I'd have is that the title div is class "description" which is very common and picked up unintended styles from the theme (Suffusion) I'm using which I had to reset. Also the markup is placed after any containing element you may have put the slideshow shortcode in but all the slideshows seem to do this so maybe this is implementers not wanting to expose themselves to simple user errors.
If I'm still using it in a few weeks time I'll deffo donate a few quid. Ta!