Is the platform level boarding with the Superliners its whole length? It kind of looks like it's only level in one segment there in the last pic.
Bizarrely, they seem to have level "mini-highs" for some cars (and not others). This seems like the result of a miscalculation to me.
The rest of it is still very very close to boarding level, though; less than the height of one step on a normal staircase. I haven't been there, but looking at it, I think this might only be a 3 inch difference. People with canes and so forth will have no problem. At spots without the mini-highs, people in wheelchairs will probably need a small bridgeplate/ramp, but shouldn't need a lift.
I would say "This should save a lot of time on boarding", but the train sits for a long time at Denver anyway so it probably doesn't matter. :-/
I'm glad to hear that people are allowed to wait on the benches on the platform. As it should be.
Worth noting: although it will probably never happen, if Amtrak ever needs to run single-level equipment to Denver, it could theoretically be platformed in tracks 1-3 or 6-8 and have level boarding. The "commuter rail" which is using tracks 1-3 and 6-8 is basically the same rolling stock as what SEPTA uses in Philadelphia (including electrification), and SEPTA stops along the Northeast and Keystone Corridors are shared with Amtrak.