M T Black is doing just about everything right in this product page. The product page tells you exactly what you are getting, and the full size preview is expansive enough to show you what you are getting.
I would suggest page screenshots, but they do appear on other product pages. The gain with screenshots is that some people will not think to click the full size preview.
I also like the consistent covers across the series.
The footers look good and will help drive cross sales.
If you want to learn how to do stuff well it is better to learn from someone who is already doing it right!
What was unusual about the adventure I picked out was the complete lack of art. Art is an eternal problem for small publishers. The apparent success of this title demonstrates that it is not needed, as long as the adventure stands on its own two feet.
The place to put the art is the front cover, that is where you want to attract the attention.
In copy writing we use the acronym AIDA. Attention, Interest, Desire, Action.
Great cover art is where the attention comes in. The playtesting quotes are part of the interest and desire stages. DTRPG does not give you any control over the action, we have one default buy button and that is it. Despite that, this is a really good example of a product page done well.