I love subways! Not the sandwich shop, the train!!!
I've been taking the Metro a lot here in Tokyo. It's the way to get around this huge city.
I've ridden subways in London, New York, Paris, Mexico City, Madrid, Washington DC, Boston, Chicago, Philadelphia and Montreal... and I have to say Tokyo is among my favorites! Why? It's easy, clean, quiet, fast, and cheap! An average ride costs under $2. It's very easy - signs and station names are posted in English and Japanese. (I think that's very considerate.)
Everyone rides the subways in Tokyo - in fact, it's the most-used subway system in the world -- almost 3 billion train rides a year!!! (That's a lot of cars that are not on the road! Less traffic, less pollution.) With all those riders, you wouldn't believe that it's so clean. No litter or dirt. None. And it's so quiet, you need to whisper when you're talking to your friends. (Really!) Finally, the Tokyo Metro is also very safe. Riders stow their bags on overhead racks, then take a nap. Look closely at the top photo - what do you see? I'm told nothing is stolen, and lost items are turned in. And riders are courteous - they actually stand in line waiting to get on. Definitely, Metro is THE way to go!