I really like Tennokai
It's busted as hell but I really like it. It's a simple change in the overall gameplay but having to look out for this quick popup and being rewarded with a free heavy attack is such a neat addition to the experience.
I've pretty much switched to Naramon on all frames because of it.
I really like that it advances melee beyond just "spam E".
Haven't gotten around to trying it out much yet. Is it really that impactful?
Absolutely, you can completely ignore melee efficiency now since you get free fast heavy attacks every few seconds while attacking.
I dunno about impactful, but it feels good
I've got a really nice tennokai setup with a paracesis, Tek Adarza, and magus aggress. Melee feels way more dynamic and way less stressful than the bloodrush meta; I can swap to melee whenever I want and do sick combos, rather than being obligated to keep the normal attacks going forever. I'm a fan.
I haven't gotten around to play with it much yet, but yeah I quite like it so far as well. Great to have bit more depth and power too for melee. I did have turn down the whatever effect intensity setting though, it was hard for me to see the flash on a more busy missions.