That trailer looks like a trailer. It's kind of hard to make any sort of judgement on the game when virtually nothing concrete is even shown.
I've purchased and played virtually every Tenchu with the exception of the Japan only Tenchu on the PSP and Tenchu Z. Every time I play one of those games it's like stepping into a time warp and re-experiencing late 90's 3D all over again.
The idea of being a ninja and scaling huge environments undetected, leaping out from the shadows for the kill and slink unseen back into the darkness is so damn cool but the core mechnics haven't evolved at all. Why is it that the modern Tenchu games still use the same clunky controls? Why haven't the platforming and combat evolved at all? It's like every team that's ever worked on these games purposely ignored every advancement made in 3D games in the last decade.
Why does Prince of Persia move more like a ninja than Rikimaru and human tank crew? Evovled platforming mechanics like wall running and the likes could lead to more adventurous level designs and gameplay solutions. I understand that direct combat isn't the purpose of the games but there are boss confrontations and perhaps the moments where you screw up, so why is the combat system still so clunky? You are a ninja, you should be able to dance around average foes and with deeper mechanics maybe the boss fights would be meaningful. Stealth would still matter over all for the ratings at the end of the level, it just wouldn't hurt to have better combat.
My disatisfaction with the series aside...
Maybe now that Acquire's developing the game we will see some sort of advancement in the series.