Disnyfanatic, I would definitely recommend ADRs for tea - I think it fills up pretty good, and I've heard of people without them being turned away.
Loralie, it is definitely on the girly side, but I did see some boys there with their families. Maybe if you just don't talk about it being girly he won't care. As far as how long it takes, we were there about an hour, but if you don't order the Grand Tea or the Buckingham Palace (which come out in courses), it might not take quite as long. The service is obviously meant to be at a leisurely pace, which makes it nice and relaxing.