It was really interesting, the best time to go is when all the cherry blossom is out in March/April. We found that you can definitely get by in Tokyo without speaking any Japanese as a lot of people speak English and a lot of the signage is in English.
My number one tip though is to make sure you get a WiFi hotspot that hooks up to their 4G network, it's pretty cheap for a couple of weeks and allows you to get around with Google Maps and Google Translate; you can pick them up from the airport when you arrive if you book them in advance.