I started using (the then shareware) Paintshop Pro (version 2?) way back in the 1980's. In those early days its' file format conversion and browse facilities were simply unrivalled.
As time went on, and my photographic needs became more sophisticated and ambitious I kept being told that I should migrate to Photoshop. I did this several times, but have always returned to what seems an equally versatile but more intuitive and easily learned product.
Most recently I invested in Photoshop CS instead of upgrading from Paintshop Pro 8. Yet again, I have reversed the decision and forsaken Photoshop for Paintshop Pro 9. I fail to see any relative deficiency in the product. Maybe it is because I learned Paintshop Pro first that I find it so much easier; but I do believe it to be the superior programme. Working methods may differ, but the many features of PSP including masks, layers and plug-ins really do offer the same range of creative options. As it is so much less expensive than its' rival, and does not require an irksome product activation procedure - it seems surprising that more educational institutions do not adopt it as standard. It would be good to see more high quality books describing and inspiring the use of Paintshop Pro.
I am very happy with PSP and see no value in spending considerably more just for the satisfaction of using the "industry standard". On Amazon the bundle with Photo Album 5 offers particularly good value. (For raster digital art I use Painter IX, which complements it splendidly.)