It's important to understand that the Introducing series is in the business not of teaching you the entirety of any given subject, but merely introducing you to it. This, as with many other titles in the series, gives you a very quick summary of the movement and its history and touches on many of the significant branches. Believe me, you can always go deeper, and really one ought to if one desires anything close to an actual understanding of the subjects the people at Totem Books purport to introduce.
What I find is that these books in general, and this title specifically, prepares your for deeper reading by giving you the gist of things, and thus allows you to engage other texts with greater sustain and keener acumen. There are other series of course, Cambridge has their wonderful, if frequently denser, Companion series, and Paul Strathern has made his career giving a similar gist in 90 minutes. I would say that the people at Totem have hit the so-called sweet spot with these though. Strathern is too often concerned with biographical detail for my tastes, and spends less time with the ideas themselves (though of course the life of a thinker is important to understanding them. Cambridge has wonderful guides, but even these may be a tad much for someone merely seeking to dip their toe in and take a look around. This is why I recommend this series.
The graphic approach hopefully renders these concepts more accessible to a wider audience, and can indeed make what are often thought of as dull subjects, quite entertaining.