For photo viewing, the original is perfectly fine and I haven't had any problems with mine to suggest that the iPad 2 could offer a vastly improved experience. The screens are essentially the same, and the iPad doesn't have any performance issues with browsing photos.
In terms of web-browsing, using the iPad 2 is going to result in a noticeably better experience. Web pages will load faster, and due to the increased amount of RAM, you'll be able to cache more pages so that you're not frequently reloading pages if you're browsing between two different sites.
Essentially any activity that requires loading or rendering large amounts of data is going to be better on the iPad 2, but anything where you're only sporadically interacting with the device or offloading the work to some dedicated hardware on the SoC (video, audio, etc.) isn't going to see the same performance gains.