Gut is a fun light read; it’s not in-depth or academic at all — it doesn’t even have an index! — but it is fun and informative for a layperson. There’s no technical stuff here that isn’t explained, and there’s a fairly light tone to all of it, sometimes quite irreverent. Sometimes, however, you can’t really say it’s irreverent because it’s full of an enthusiasm and awe for our digestive system and everything it can do.
My main quibble was that it was too casual, too light, too much for the layperson. This wouldn’t be my chosen field even if I wanted to, but with just a couple of other books covering similar topics under my belt, a lot of it was just boring. (For example, for stuff on microbes, go for Missing Microbes by Martin Blaser, instead. Much more informative and in-depth, albeit not so easy a read.)
It’s fun, and it probably works well for the intended audience; I’m just not that audience, really. I did learn some interesting facts, and the diagrams/illustrations are pretty fun.