Tokyo is the capital of Japan and is its largest city, with a population of somewhere around 12 million. It is an extremely busy city. Tokyo was almost completely destroyed by bombs during WWII, so much of the city has modern architecture. From what I saw, most of the traditional style buildings, such as temples and shrines, have been rebuilt in the last 50 years. There is still plenty to see, but don't expect to encounter traditional Japan as you would in Kyoto, for example.
Best way to travel around Tokyo is by subway or train. A JR rail pass doesn't cover the Tokyo subway, so be prepared to pay cash. The subway ticket vending machines do not speak English. However, fare adjustment machines do. What that means is that your best bet, if you're not sure how much to pay, is to buy the cheapest ticket (160 yen, I believe) and then insert it into a fare adjustment machine before you exit. You buy a ticket by putting money in the machine until a button with the fare you want lights up. When it does, push it, and a paper ticket will come out. Be sure to take the ticket out of the gate as you enter, because you will need it to exit. Overall I found the subways not as English-friendly as JR, but far more extensive around the city.
Some of the major attractions in the city I have individual entries for. These include:
- Tokyo Imperial Palace and the East Garden
- Meiji Shrine
- Asakusa Kannon Temple
- World Trade Center Building Observation Deck
- Sumida River cruise
- Ginza Shopping District
- English language bus tour (Hato Bus)
There are other things to see in Tokyo, I'm sure, but I can't say much about them, since I was never there!
Overall, my impression of Tokyo was that a day and a half to two days was enough to get a feeling for this city. I would recommend allocating more time for Kyoto.