I was skeptical of the title. (Really, since it links directly to stripe.com, and with HN link title guidelines, my immediate assumption was that they'd written an obnoxious blog post.)

Immediate impressions:

1. It loads really fast!

2. Really dig the color palette.

3. Good typography and spacing for the most part.

4. There's some weird UI elements, like the slightly shaded background on the link just below the nav.

5. I like the non-device-specific screenshots, but they are pretty pixellated on my 1440p screen.

6. I could die happy if I never see a gears icon again.

7. Use of animation is a mixed bag. The hover menus are pretty and behave nicely if you intend to access them, but there should be a brief delay before they open in case I'm moving my cursor past them. (Preferably menus should be opened with a click/tap.)

8. I'm not using Stripe, so I can't really evaluate the docs as a real user. But they look nice and they're very readable, which is a damn sight better than most of what I'm used to seeing.

8 addendum. The single expand/collapse side menu is disorienting though. It creates moving targets to reduce noise.

8 addendum 2. Boy it was confusing that the "stripe docs" logo is two distinct links.

Overall very visually compelling. I'm still super impressed with how quickly things load.

I hate to be a negative person, but what is it with web designers completely ignoring accessibility? It's built in to the browser!

Stop removing the damn focus outlines .... http://a11yproject.com/posts/never-remove-css-outlines/