"Post Comment" button

I’m afraid that’s not possible at the moment. Jetpack’s Comment form is added to your site via an iFrame. As a result, you don’t have full control over it, and can’t change its design. You can, however, choose between different layouts under Settings > Discussion in your dashboard.

We’re planning on adding more options to customize the Comment form in the future, so keep an eye on the plugin changelog!

I was wondering if there has been any change in regards to styling the Jetpack comments form?

An update on this issue would be nice.
I’ve had to disable it as it’s just so butt ugly.

Is this feature available yet or is there an ETA on it?

The existing button design violates nearly every best practice for designing submit buttons. It’s small, blends into the background, and is easy to miss. The excessively rounded edges makes me feel like it’s 2001 and Apple just released the first ever iPod. The ability to customize the “Post Comment” button really is essential to widespread adoption of the Jetpack Comments plugin. Hopefully this will be possible soon…

@leafcutter It’s still not possible I’m afraid. Until we offer this option, I’m afraid the only solution would be to disable the Jetpack Comments module under Jetpack > Settings in your dashboard.