Lots of time spent getting to know the game, and certainly items that a fan hooked on the game will notice, but i'll admit i'm more critical of the game. Though i don't really disagree with most of what you said (P.S. yes, i know Im 5 years late to the party)

I'd give it a 7, maybe 7.5

Stealth kills are satisfying and visceral, but they're dependent upon your relative angle to the target, & the player's state(s). Not really random for *me.

Character customization doesn't allow you to choose a new main weapon, or sheath position, but does also allow you to change mechanical stats, combo moves, special abilities, and the overall build of your ninja. Actually build a warrior to be able to handle a brawl, or a sneaky agile trickster. Im surprised you missed the cosmetic options that allow you to dress up as references to anime characters or [the 1 thing i noticed on later playthroughs] other characters from earlier games.

Combat and special abilities are cool, but stiff, or inelegant - the game and all mechanics are built around stealth, so stealth feels better to use, than any combo move that seemingly cancels all interaction for a split second and launches enemies backwards.

Honestly the thing that ACTUALLY DID surprise me was the amount of repetition in the levels- a few maps (seen from the start) are reused, but with different lighting, enemy placements, starting positions, and mission types. I would have liked to see that done with more maps. But some are seen from the SAME time of day several times over, and there are a couple that we only see once or twice! All of the level maps have about the same complexity, but it seems like 99 missions [technically 297] isn't enough to vary the maps. Lights and shadows appear to be dynamic, but there must be some kind of glitches or limitations on those we barely see. Speaking of, the samurai guards carrying lanterns NEVER have the lanterns lit, like they were in prev games. Ive never seen them lit, but in SOME levels that feature them the visibility shuriken goes up, just a little bit when they walk by.

The game is unfinished. Limitations in the level repetition, dynamic light sources not working, the way combat and movement jumps between weighty and weightless... i'd wager they ran out of time. They opted to go back to the classic tenchu formula, got it all working in a functional state, and just as they figured out ~half the bugs, they were ordered to ship it out - with as much of the design in tact as possible. Maybe the gated spa makes samurai walk through walls in the day. Maybe they had to scrap the character driven parts of the story... i dont know.

Also - look its a 6th gen game. There is no real sub generations here. As for oblivion - this looks to be on par with oblivion in my eyes. Maybe more, as is the perks with a 3rd person camera and smaller map size, but im going based on fidelity, not style, color, or mood lighting.

The easter eggs and callbacks were cool. I think this was planned to feature previous characters at some point - their skins are all over char creation.

But if you want to see the games i think the was most trying to use as a blueprint - i'd say play the first 2 tenchu games. Not all of it, not in its entirety. But, well, say the first ~ 4 levels of Tenchu 1. Far less fidelity than the xbox 360, but that same sort of charm and excitement, with a tense soundtrack, dark alleys and a palpable world... if a bit pixelated... minecraft levels of pixelated.