Yes, by all means go. Tokyo in general is an absolutely wonderful city to visit, and if I only could, I'd go again and again and again.
Tokyo
Disneyland and Disneyseas are less than an hour north of downtown Tokyo (depending on traffic, and for example from the Ginza area) but the connections are very good. Tokyo Disneyland is based on the original Disneyland and on the Magic Kingdom in Orlando. Perhaps the main difference is that more of it is roofed; depending on the season, it can be quite rainy.
Disneyseas, as can be expected, tends more to the educational (think Epcot) but is still very entertaining. Disneyland and Disneyseas are located right next to each other, within walking distance. First-timers could spend a day in each, but if you've been to Anaheim or Orlando several times, then you could conceivably do both in the same day.
There is absolutely no problem in getting yourself understood with English. I have yet to meet a single cast member in Tokyo who isn't more or less fluent. Furthermore, all of the attractions are designed so that also people who speak English can enjoy them.