I like what I'm reading.

Tenchu Z was indeed a let down, but it wasn't a bad game and I still enjoyed the time I spent with it. The best titles in the series are Tenchu 1 (particularly Shinobi Gaisen, the Japanese release of the American version with an added level editor), Fatal Shadows, and while I know I'm going to get a lot of "WHAT THE FUCK!? U CRAZY MAN, CRAZY!" responses, the PSP Tenchu also rocked. Despite the draw distance issues (which were the same as the PSOne games, so whatever), the game was packed with levels, tons of playable characters, and an awesome, awesome level editor, complete with music from previous Tenchu titles. I really hoped that the Xbox 360 game had all this stuff, but it dropped all of that in favor of custom characters (with less play styles than before, grrr) and the limited multiplayer.
If you want some ninja goodness closer to the original games, give Shinobido a try. The series is made by Acquire, who developed Tenchu 1 and 2. The first game came out in English in the UK; there's also a PSP version called Shinobido Homura which is more straight-forward than the console games and has a level editor included as well.