I'll read it. It seems like the type of book (I read pretty much everything but romance and horror) that I would pick up, even if it wasn't by J.K. It's like Liz stated, I've read books written by authors that have written entirely different series' and found myself happy with the results. Twilight, for example, sucked, but the other stand-alone that she wrote, The Host, is actually pretty darn good.
I'm excited for it, and I know I will be buying it. I love me some mystery. I'm pretty sure the only thing I would find myself comparing the HP, however, would be her writing style (since it is written for adults and not 'children') and her character depth. Then again, I compare a lot of other books that I read to HP, and I actually use her in depth knowledge of her characters are a model for how well I should mold my own for the novel I started.
Can't wait to read it.