Let me start by stating my experience with houseplants: I've killed a few over the years, but am at the point where I keep my plants happy most of the time and rarely have a lost cause. These days, I'm confident enough to buy plants that are not labelled "beginner" and rescue friends' dying succulents. On the other hand, I don't consider myself "advanced" in plant care and still have lots to learn. As such, maybe this book wasn't aimed for my experience level: despite the adorable art (which I loved), overall I found it kind of childish and simplistic, with few usable tips for the intermediate-level plant enthusiast.
A lot of the tips and fun facts were so basic that I'm not sure whether the author is really an expert or just an enthusiastic afficionado who wrote a book. Additionally, they were split up very strangely: some plants were in the "watering" section, others in the "repotting" section, other still in the chapter about light... It makes it hard to navigate, and is far from optimal. All of the tips seemed to be for only one type of plant, which was a strange way to split up a chapter about care. If I know how to water a ZZ plant and how to repot a Monstera, but not how to water a Monstera and repot a ZZ plant, I'm not doing great...
While the illustrations were cute, they were few and far between. I would have appreciated an illustration of each described plant; while I do know many by name, it isn't all of them, and a visual reminder would have helped, especially since this book is so beginner oriented.
The tone of the book kind of feels like a 200 page Buzzfeed article. The author is constantly cracking jokes or making puns between factual tidbits, and the humor is sometimes juvenile and not really my cup of tea. Interspersed within the author's opinions are quotes from other houseplant people and references to NASA's research on houseplants. Considering Buzzfeed's popularity, I'm sure this writing style appeals to some people, it's just not to me.
In conclusion, while there wasn't anything factually wrong about this book (as far as I know), it certainly wasn't in depth. Maybe good for a teenage, beginner plant lover who has never even googled "how to care for a houseplant", but not for someone who already owns a few plants and is looking for some extra pointers to add to their knowledge base.