As a fan of the series, I must admit I found the trap genre quite awkward, but I must now admit it's in fact quite fun!
However, when I started playing the game kinda grew on me. It's got all those characters I loved from the older games, missions related to other titles in the Tenchu series and several interesting weapons. The puzzle itself is extremely simple, and perhaps a bit too easy, but the online mode is extremely fun. A semi-bomberman style ninja game that is great for parties. A total blast IF, and mostly IF, you have people to play with.
I think developers should be encouraged to innovate, so giving this game bad reviews because you don't like the genre or it's too different from the other titles isn't a very good move. I think it's a nice little game, even if it's not exactly successful or great.
All in all, a great game for open-minded fans of the series.