Highly recommended and a great way to see the Boso peninsula... Did it last year as my first ever organized event ride. Would suggest getting your own accommodation, though, to save a bit of money and avoid being packed into rooms with multiple strangers.
This year I'm thinking of doing it again, but with a twist... (posting thread now).
(Oh, and if you really, really want to, you can try to spot yours truly looking extremely Fredilistic in baggy shorts and toe clips on this page: http://www.tour-de-chiba.jp/report/)
The young boy did all 3 days and was the featured story on the Chiba news for the event. Lovely little kid. He comes to our Sunday morning sprints and tries his luck. Also participates in long weekend rides with the club too. Really amazing that people of all ages can come together and enjoy cycling. These kids that come to our club grow up fast and become confident independant individuals. My sons however hate cycling.... I hope he keeps it up into his teens and 20s...