I guess it all comes down to need V's want. I don't NEED the iPad but I would not give it back.
I use it at home as a bit of a nerve centre for my home entertainment stuff and also watch TV or movies on it. I use it so much that I am trying to find a nice wall mount for it but as yet nothing seems to have been developed.
At work I use it to take notes in meetings and generally store "to do" lists. Sure I could do all this with a laptop but it is just so much easier to use the iPad.
I have just discovered the joys of ebooks as well. This keeps me sane on the bus trip to work...I have actually tried the ebooks on the iPhone, iPod and iPad and the iPad is streets ahead. I know I could get a kindle for less but then the kindle doesn't do all the other stuff as well.
Thing is, I haven't used my iPod Touch since I got the iPad though. In all honesty the iPad is just a big version of of a Touch (at least the WiFi only one is) so I guess that would mean I agree. You don't need both - but for what I use it for, it is much better than the Touch.