Which Nano are you trying to upgrade from?
Why do you want a Touch?
If you want a larger screen and want to stay within the iPod family, yes it is worth it. However, you may see new or refreshed iPods that could be cheaper per GB in another 6 months or so and kick yourself for paying $300-$500. If you can live with that, by all means go for it. You could wait and see what happens in the coming months or investigate non-iPod options from companies like Cowan and Archos that offer more.
By the way, I have the 8GB Touch. I love it, but since it's only 8GB I mainly use it for movies and a few podcasts and selected music playlists. I like using it in the car since it is fairly easy to control while driving, though I really don't recommend doing that. I still use my 30GB video iPod for music. In a pinch, I'll use the web browser, but I still prefer using my laptop.
Another consideration is getting video content for it. Are you willing to pay the iTunes Store for it or can you get content through other, possibly illegal means? If the answer to both is "no", then it's not worth it. What's the point of the bigger screen if you have nothing to watch on it?
should I Stick with my ipod nano Or Should I UPgrade To A ipod touch?
and is the Ipod touch really worth me upgrading 2 It? THX Alot