Well if you have 1.50 on your psp DON'T upgrade. I myself baught my psp as 1.51, and as you know, anything above 1.50 will not be able to boot homebrew ( No custom apps, emulators, and anyother thing developed for psp.
Now 2.0 has a web broswer and some other add-ons, but imo it still needs a LOT of work. It needs more supported audio/video formates, and more support for the web browser. If you do have 1.51 or above i definatly recamend upgrading, but keep your 1.50 if it is 1.50.