I didn't have a chance to go inside this time, but I have in the past. Inside the tower, there are a number of shops and restaurants. At the look out, there is a glass panel on the floor that will give you a view of the ground below. If you are afraid of heights, I wouldn't recommend looking down through the glass panel on the floor, but it is a good experience.
If you are interested in visiting Tokyo, at the moment, entry into the tower is about 1,000 Yen. Tokyo Tower closes earlier in the evening though, so this may be more of a day activity or one in the late afternoon before 7 p.m.