Discover takes your listening history and library content into account. Currently, it only recommends content within your library, so the quality of recommendations will vary based on how much content you have, and especially, how much unfamiliar content you have.
As @extracampine noted, lots has been going on, but not with respect to our core metadata/library management experience. This is the function of being a small internally bootstrapped company with limited resources to tackle all areas of the product at once. This is changing–we’ve hired three employees in the past month, including a developer with a data science background who is dedicated to the metadata and library management areas of the product.