According to my personal visual check in Apple Store:
Jet Black is surprisingly reflective especially after some body oil getting on the surface, it is very hard to tell if it isn't the old SS JB
It is notably not the same coating finishing on the iPhone 7, and at least with the demo units I can't see it being scratched already (where the black Ti 16 Pros on the iPhone isle are scratched as hell)
Natural Ti is more than just slight tint, it obviously cannot pass as silver
Slate Ti is not as dark as SS JB, or even the S10 alu JB but they look very close if environment is low light
So they are really close in how dark they are; I was wearing my S7 SS graphite, its darkness sits right between natural and slate Ti
For anyone looking for a shinny / as bright as possible finish, you have to go for Hermes this year
By the way, all the in store Hermes new bands except the Grand H, are waste of time IMO lol. Just get a leather band through Hermes
The Ultra2 black has a rougher touch than natural Ti
Two demos units I saw both had small, white scratch marks. it is hard to tell if they are permanent but they are very visible
The new Ti Milanese for Ultra is very nice. It feels structurally sound but light weight, the cobra buckle is well made, it's a bit hard to put on and even harder to adjust but feels great when worn