This is the first anthology I have read, and boy was it a good one! All I can say is that if you are a fan of science fiction, fantasy and paranormal, then you should give Irregulars a shot. I am familiar with two of the authors involved (Josh Lanyon and Ginn Hale) and was thoroughly impressed with Nicole Kimberling and Astrid Amara.
In my opinion, each story gets better and better. The world building is rich, with the paranormal and fantasy elements having become part of scientific protocol and regulations of the NIAD. The characters are varied with each story consisting of a pairing of NIAD employee/agent with a non-NIAD or paranormal character. There is some conflict or mystery with each story that comes to a satisfying end. I would recommend reading the story in order (or at least leaving Ginn Hale's story for the end); the reason being that by Things Unseen and Deadly (TUAD), you have the return of an agent as a secondary character, mention of the other agents, and mention of an ancient artifact from another story. In a way, TUAD is a nice way to tie up the stories that precede it.