I used photoshop 'elephants' 3 for ages, I really liked it. There were just 3 things lacking which finally caused me to buy CS3, namely:

1. More brush dymanics - CS3 gives you mountains of controls when creating custom brushes.
2. Pen tool - I needed curves
3. Alpha channels

I have PSP XI and Painter IX.5 and they have some cool features that CS3 doesn't have but they've both always felt a bit 'flimsy' to me, in the same way that  cheap plastic power tools feel flimsy even if they have nice features. Photoshop has always felt like the real deal, industrial strength, particularly when I need to work really fast.

Bear in mind if you know someone with 'big photoshop' you can create fancy brushes and layer styles on their machine and save them as presets to use in your 'little photoshop'.