Charles Yu (the main protagonist in this story as well as its author) is a time machine repair man. Travelling in his Recreational (or as the main charater suggests, should that be re-creational) Time Travel Device model TM-31 accompanied by TAMMY a rather unhappy operating system and Ed, a dog who doesn't really exist, he fixes problems that other people have with or cause through their use of a time machine - but he is unable to fix his own problems.
The first thing to say about this story is that to me, it is not a real science fiction story. The author describes Minor Universe 31 as "a core of reality wrapped in a layer of science fiction" and to me that describes this whole book. The book is really about relationships. It describes and explores the authors relationships with himself, with TAMMY, with Phil (his manager who is actually just a piece of software - Microsoft Middle Manager Version 3.0), with his mother, but primarily with his father.
The time travel element of the story is just a plot device to enable the author to go back to key points in his relationship with his father and to observe (but not to participate in) them again. There is also a fair degree of discussion around determinism versus free will especially concerning the author becoming trapped in a repeating loop of time.
Personally I struggled with this story and at several points I almost gave up, but other reviewers mentioned that it gets better towards the end, so I kept on reading hoping it would get better. I also found some of the science fiction descriptive parts of the story to be unnecessary techno-babble that really added little if anything to the story.
On the presentation side, the Kindle presentation is exceptionally good - the story features quite a few drawings and diagrams and these are faithfully reproduced, also there are several links to footnotes that work perfectly too, even if they are quite easy to miss. Also, make sure you page back from the initial page that the Kindle first opens, as there are a few things before the first real page that you should read.
Overall: Two stars - Science Fiction is my first love in literature, but as I said earlier, I really don't class this as a sci-fi book. I finished the story eventually even though it took me almost a week as I could only cope with reading a few pages at a time. It did get slightly better towards the end but I certainly won't be reading it again and I would not recommend this story to other hard core science fiction fans.