Negatives: Clark Ashton Smith levels of flowery language.
I'm not sure I see that as a negative.
Of the Weird Tales triumvirate, I would argue that CAS was the most technically capable writer.
Speaking of HPLHS, I recommend Andrew Leman's new podcast Voluminous. I'm rather enjoying the podcast. I like the curated aspect of the presentation of the correspondence, as I randomly perused some of Howie's letters last time I was in Providence. There's not enough time to think about a reasonable approach, because the collection at the John Hay Library is impressive.
If y'all want to hear a little more about C.M. Eddy, the episode "Tidings of Comfort and Joy" provides some further insight.
https://www.hplhs.org/voluminous.php