With "universe" in the title and a yellow rubber duck on the cover, comparisons between this book at Douglas Adams are hard to avoid and may have been intended, but this is not another Hitchhiker's Guide although it does have a bit of the atmosphere of a Dirk GEntly book.
This is nominally a science fiction novel, but it is not 'hard' SF. There is no real examination of the science behind it and the situation of having two alternative universes that can be travelled between is just a plot device to create the right circumstances for a comedy detective story.
I found it all quite enjoyable even if the detective aspect was not particularly mysterious or thrilling, the science understated and the humour gentle rather than guffaw-producing. Certainly a decent first novel which, after the first few pages of establishing the circumstances, had me ruashing through to find out what happens.
As the author had a PhD in electrical engineering I figure she knows a bit about science and I had a sense that she was struggling to keep it out of the book where it would have only got in the way. Enough science does sneak in for you to have a few "what if..." thoughts about it all, and enough hints are dropped to explain why there are only two universes when the most likely options are either a single universe or an infinite number - the answer being that there are an infinite number but only these two have a link between them. (OK, actually there would be an infinite number of other linked pairs, but now I'm starting to get bogged down in the science)
For me, the best science fiction is not about the science but about human response to the science. In this case the concept of having a mechanism to travel between two alternative universes doesn't result in everybody acting like Prof Brian Cox and being in awe and wonder - society's response is to set up a huge and intricate bi-univeral bureaucracy with undertones of totalitarianism. The reasons for this are hinted at but I would have liked more exploration of this, though I can see how that would derail the story a bit.
On a personal level, the main character has a little bit of the Arthur Dent about him. Faced with the prospect of having an alternative copy of himn in the other universe, his preoccupation is with whether his 'alter' has written the book that he keeps meaning to write. Even in the face of mounting evidence that he was personally responsible for the whole creation of the alternative universe, and growing suspicion that somebody is trying to kill him, the hero still remains fixated on this triviality.
This idea that, faced with amazing circumstances, humans remain doggedly human is what I liked best in this very readable book which should probably be read on a Kindle for reasons that will become clear before the second chapter.