It is a bit of a dilemma. The ipad's larger screen means that it can have apps that do things that you wouldn't necessarily want to do on the small screen of the ipod (I have an app that lets me keep my sheet music on the ipad as a gig book, for example), but there is the problem that it's a lot more to lug around. On the other hand, the camera in the ipod is nice to have, at least for video (stills are pretty mingy, compared to the camera in the iphone).
If you're young, with great eyesight, the ipod is a lot handier to keep with you all the time, but it sure is nice to have the larger screen of the ipad. Really, this is something you'll have to decide for yourself.