Wether or not you find Tokyo fascinating can depend on what you are used to.

I just got to Tokyo less than a week ago, and the scale of things, size and all the people is a very fascinating experience for me. Tokyo has 3 times as many inhabitants as my entire country! So the scale of everything was mindblowing!
Just buying office supplies in Ikebukuro felt like a venture in and by itself.
I havent quite settled down yet, so i really haven't done anything.

I got the Lonely Planet book for Tokyo, and it is litteraly FULL of stuff to do.