you do also have to start a new character (and when version 3.0 is released my understanding is new characters will have to be started for that as well if you upgrade) all in all though I would definately say its worth it.
It really isnt actually that much work, takes a while to install, but thats probably in part due to my low end computer. and Fallout 3 wont run on my computer but i can play it with TTW. the only thing i liked better about NV was crafting, weapon mods and some of the armor/weapons. I think its great, I prefer the atmosphere in Fallout 3 to that of New Vegas quite a bit.
