This short time travel novel hits all the points and paradoxes - altering the past, witnessing historic events, making money with future knowledge, and encountering yourself. Described as the ultimate time travel novel, this seems more of an exploration - the very self-focused main character lacks a conflict, and the story suffers for it.

In the opening paragraphs, the main character is cautioned to keep a journal, and this novel is told through a series of (undated) journal entries. This stream-of-consciousness approach works for this story, and the points where it is hard to follow are intentional. It also manages to pack in most of the time travel tropes in a fairly short space, and can easily be read in a few hours.

Heinlein's All You Zombies is shorter and has at least a mystery. This novel hints at that mystery but never completes the circle, and for me is the worse for it. Overall rating 3 stars, but a future self seems to have edited this to be 4, and I can't really argue with him, because I like him so much.