He still hasn't fixed the squished screenshot's obviously wrong aspect ratio, at least as of the time I am writing this.
Screenshots with incorrect aspect ratios are a huge pet peeve for me and while this may not be entirely rational, it is one of the big things I find myself judging someone's overall competency on when they screw it up and they are doing design-focused work. I'd rather have the whole page be written in Comic Sans but have the screenshot in the right aspect ratio because at least that's a choice rather than just shoddy work.
He's received some useful feedback in the comments here.
That's the whole agile/lean idea: get user feedback early rather than spending a ton of time polishing it in isolation.
The agile/lean idea is not to have your users bug test your code! It's a technique for gathering feedback early and often in order to make sure that the requirements are sufficiently addressed. What you are describing is a shoddy work discipline which no self-respecting developer would even think of associating his name with.
More appropriately, one of the central pillars of agile is to be in a releasable state at the end of every sprint.
I'm replying to a comment about the framework needing more "polish." It isn't like he's releasing a version to the general public that crashes your browser.
If you look at the feedback, it's mostly stuff like fonts, spacing, etc. I think it's quite acceptable for a developer to get user feedback about the interface on v0.5 of free software.