His writing is terrible.
The stuff HPL was publishing in the 30s was actually pretty typical of pulp SF of the time. (Dire.)
One wonders what he would have written like if he lived long enough to write for Unknown Worlds.
When I opened up a book and started reading a story titled “The Dreams in the Witch House”, ‘Whether the dreams brought on the fever or the fever brought on the dreams Walter Gillman did not know’. It was interesting from the start.