I have been pretty impressed with the original programming that Netflix has been creating over the past couple of years; even shows I don't like are still very well done.
However, they really should not have created Shadowhunters; or, at least not done it the way they did.
It has to be one of the worst things I've seen since that travesty Star-Crossed (not to be confused with The Starlost; which was a kind of terrible, yet interesting, 70s sci-fi TV series which I wish someone would absolutely remake - along with Otherworld, a horrible, yet very interesting 80s sci-fi series). At least from the CW network I don't expect much better than what that turned out to be; but I was hoping for something a little more from Netflix. Now, I realise that Shadowhunters was based on a series of books (which I never would have read, and now definitely never will - while YA dystopia/spec-fic is fab, supernatural stuff is awful), and things do get lost in translation; but there isn't enough of that to use to disguise the cliche story, bad dialogue, and worse acting. It ranks right up there on the contrivance meter with that Terry Goodkind adaptation Legend of the Seeker. Stories like that never feel fleshed out (which is what saves Game of Thrones sometimes for some folks, because the flesh is out - all over the place - whether you want it to be or not), always feel like they're trying way too hard, and the characters are always a little (or a lot) over the top - they are always 'types', rather than people (or characters, or creatures, or something else); which is why I don't like superhero stuff. I can't abide the over-the-top typeness of the characters.
So, if you liked the Shadowhunters books, don't watch the show. If you liked Star-Crossed, you need a reprogramming of your taste. Give them both a miss, you'll be all the happier for it. But if you know anyone that's in a position to pitch to a network to have a TV series made, have them look into The Starlost and Otherworld. Please.