I found "Shadows" to be an excellent sequel to "Ugly", in Teasdale's "Ultrahumans" series. The focus changes to Cygnus' partner, Twilight. Cygnus remains in the background and continues to develop in the overall story arc.
In "Shadows" we learn Twilight's origin story and the progression of her powers. The plot is good, your basic heroine chases the bad guy, both Ultras, and, of course, is victorious.
What is more evident and important, to this reviewer, is Teasdale's skill at creating alternate realities. He is a true Master, and the world of the Ultrahumans is presented and developed further in this second book in the series. The action is great; the dialogue is snappy and snarky, which this reviewer loves, and, as a whole, this is a seductive, enticing, page-turner of a read.
If I have any concern, it is about the author himself. I find myself wondering if he is manic at times, since he has so many series ongoing at once. Regardless, Teasdale never disappoints and this book gets my highest recommendation.