This was my very first time to watch a sumo match, but I think it was really worth seeing.
You can also watch sumo outside of Japan. Although no tournaments are held overseas, some rikishi make a tour of performances. If there are any matches held nearby, I strongly recommend you to go watch it.
All the crashing battles of the rikishi who are twice as much bigger than myself, the fierce defense and offense at the ring rim, the ritual performances respectable and solemn were very impressive.
If you get a chance to visit Tokyo in January, May or September, do come see a real sumo match.
There are more chances to watch sumo: the Grand Sumo Tournaments are held in March in Osaka, July in Nagoya and November in Fukuoka.