Yeah, this was not my favorite Heinlein ever. It had such promise. I like Heinlein, I like time travel stories, win-win, or so one would think. Look, this isn't a horrible novel. It's an OK novel. The prose is serviceable, the tone is light and funny, the plot is...well it's alright. This all points to a book I will love. Unfortunately it was not to be.
The book is off-puttingly sexist in its treatment of the main female antagonist, even accounting for the time it was written. The protagonist does something...reeeeeally creepy. I can't explain it without spoiling a major part of the story but if you have read the story you know what I'm talking about. It's just fucking creepy.
Anyway, this is a book worth reading if you love classic SF or if you love Heinlein (like me), but it is not an example of Heinlein at his best.