Aaron Williams has pulled of a mean feat with this series; It has a huge cast of characters, multiple layers of ongoing and sub-plots and mysteries, and he uses a fair number of analogues for various corporate owned super-hero properties. Oh, it's also about little kids, so that should basically give it the kiss of death right there, right? Seeing as I'm writing this review, I'm going to say the answer is NO.
Now, to be fair, this volume isn't perfect: Williams isn't writing for the trades, and so stories come and go at you without the sort of "complete experience" you normally would feel with a standard trade collection that would take you through a single narrative arc. Another problem present is that if you haven't been following the series up until now, it can at times leave you a little lost. In his defense, however, he puts up the early issues of the comics up as a webcomic here, for free, so he's doing his level best to get new people caught up and into the mix. Finally, Williams hasn't quite mastered the pacing and composition of action scenes, and this is definitely an action-heavy volume.
Where Williams succeeds is in the more fundamental areas of storytelling; he is constantly introducing new ideas into the series, while developing ones from previous volumes. In this volume alone, we have a school Career Day, an Alien Invasion, and some insight into the mystery behind the founding of the school. That also doesn't include the ongoing saga of series protagonist Tyler Marlocke, which goes through a couple of new twists in this installment. Of course, a fellow student is going through a trial of a very common and personal sort, and Williams is direct in showing the consequences of such a change. Unlike other kid-centric comic properties, the kids in this series behave like children, and so they lack the maturity necessary to understand the situations they are in.
However, where the book excels is character and humor. There really are some laugh-out loud moments and there is no shortage of fun and interesting characters. However, it is the last chapter which is the strongest, as it gives us a peek behind the mystery of the principal of PS238. It has long been assumed that he held onto a sinister secret. Well, we do find out the secret, but it is far more interesting, and more ambiguous, than we've been led to believe. Other characters get a chance to shine, including some favorites, and a few that I almost believed had been forgotten.
Overall, PS238 may not seem that innovative: its' old-fashioned approach to storytelling, and it's focus on developing long term plots and character arcs seem almost forgotten in this age. But, well, I can't think of a series I have more fun reading on a regular basis.