I just finished Hammer Time Book One, and I loved it. Chances are, most of my reviews will just be me saying that I love the story.
Anyways, Martin is a great protagonist. Very amusing and relatable. I wasn't expecting such a focus on Transformers, but I certainly didn't mind it. "A surprise to be sure, but a welcome one," as they say. It was a good introduction to that part of this universe, and it seems Transformers have a bigger focus in later stories.
I will no doubt read Hammer Time Book Two next.