I decided that I nevertheless want to weigh in, even though a couple of giants have already done so.
Larry Corriea did a masterful fisking of the HuffPo article, and
John C. Wright gave his own thoughts as well.
So, Ms. Shepherd, congratulations, you've garnered some attention. Probably not the kind of attention you wanted, but when you write something that utterly, egregiously stupid, be prepared to reap the consequences from people smarter than you.
In the writing world as well as the economic world, a rising tide lifts all boats. I look at people like Jim Butcher and Carrie Vaughn and Patty Briggs and Rob Thurman, and I don't want them to stop writing so there's more room for me in anthologies. I want them to stick around because they are creating a market for the things I write too. Someday, in some far-off future when I'm actually writing novels instead of shorts, maybe some fan of theirs will be poking through the shelf, find my book, and think "Hey! That sounds exactly like the sort of thing I love to read! I think I'll check it out."
The mere fact that they exist has the potential to put money in my pocket. And this is the point that Ms. Shepherd is woefully ignorant of.
The other ridiculousness here is that Rowling's mysteries are nothing like Shepherd's. "The Cuckoo's Calling" takes place in the modern day, while Shepherd's detective is a Sherlock Holmes knockoff in 1850's England. Rowling's prose is clear and evocative; Shepherd's... well. Isn't. Look at this opening from "The Cuckoo's Calling":
"The buzz in the streets was like the humming of flies. Photographers stood massed behind barriers patrolled by police, their long-snouted cameras poised, their breath rising like steam."
I don't know about you, but I immediately got a sense of "flies around a corpse" from that even though we don't even know there's a body for several more paragraphs. I thought that was pretty neat. Not only that, but there is action here. People are doing things--interesting things. Clearly something just happened, and we keep reading to find out what it was.
Contrast it with this, from "A Fatal Likeness":
"We began before thick in autumn fog; we open now in the fury of a west and winter wind. Above us high loose clouds drive across a steep grey sky--"
And that's about when I started skimming. She goes on in this vein for a page and a half. I realize that my personal loathing of present tense is not Shepherd's fault, but the pretentiously "royal we" POV is the icing on that particular cake.
I don't pretend that I know everything about writing; I'm a barely-published short story writer and Shepherd has had five novels published. But I do know better than to open on the weather and then spend a page and a half waxing rhapsodic about it and the city street it's taking place on, in a POV that only college lit professors and others of that ilk will find endearing. There is "setting a scene," and there is "bludgeoning the reader with turgid atmosphere until they are semi-conscious and bleeding from the eyeballs."
So, Ms. Shepherd, my advice to you is this: stop bawwing about how Rowling is daring to exist in your (loosely-defined) genre, crack open her book, and actually learn how to write a bestseller from reading it. And then other wannabe writers can write whiny screeds about you sucking all the air out of your genre and how you ought to step aside and make room for them.
That's assuming you haven't killed your incipient career altogether with this ill-considered diatribe.