In retrospect, I probably should've asked this question BEFORE writing over 56k words in my fantasy novel, but here I am to ask anyway.
Is the fantasy market really as hard to get into as I've heard? Or does it depend upon how good my WIP is and how good the query/synopsis is, like it does any other genre?
Yes, it really is very hard to get into. You have to write something exceptional and something that does new stuff with the old tropes in order to make it happen.
The reason for this is because
relatively little fantasy sells. (compared to the more popular genres)Compare it to a genre like romance, where the average romance reader buys 10 - 30 new books per month, and you'll understand why romance in considered the easiest fiction genre for new authors to break into. It's not because their standards are necessarily lower (although I've read some real stinkers), but because there is a voracious market out there that demands more, more, more all the time. The publishers have to keep the demand supplied, and so they are much more likely to consider newer authors who don't have quite as much experience with crafting fiction.
Fantasy, on the other hand, doesn't have such a hungry readership. Fantasies tend to be longer and denser, so even the fastest readers can't go through all that many new books in a month. And fantasy readers tend to stick with the subgenres they like within the genre. If they like urban fantasy or magical realism, they're not likely to pick up a pseudo-medieval-European tale of a farmboy discovering he's the chosen one, or
"Knights Who Say Fuck." (I'm not knocking; GRRM is one of my favorite authors ever and I love ASOIAF. I just like the parody title.)
So even though there's a lot on the fantasy shelf at your book store, and even though several new fantasy novels are sold every year, they just don't sell as quickly or as predictably as romance, women's commercial fiction, or YA.
That being said, EVERYTHING depends on how good
your finished manuscript is. The query letter might get your pages read, but it won't get your book published. Only your book will get your book published. And yes, you CAN debut with a fantasy novel. It'll be a harder row to hoe than, say, romance, but you can still do it. And you should ALWAYS write what you love and what inspires you; don't write just to get published. It'll show, and then you probably won't get published!
Write the best book you can, and make it as good as you possibly can. When you think it's as polished as you can make it, submit it. Be prepared for a lot of rejections, because any book gets a lot of rejections, but especially fantasy by a new author. If you're prepared for a lot, then you won't be dismayed when you get them.

And remember it only takes one "yes."