First of all, a disclaimer: if you do not know that it is, this is most probably not for you. The comics deal with issues of gaming, mostly computer and console. Penny Arcade is very well known in these circles, which means that even if you have a passing interest in the subject you must have heard about them - thus the disclaimer.
The biggest problem with the comics - other than required knowledge of the subject - is that it does show its age. The first book talks about games released between 1998 and 2000; by the rate the gaming industry moves, it is practically the age of dinosaurs. Case in point: at one point they praised the early 3-D graphics which by modern standards looks VERY ugly.
I played some of the games they reference, and even in my case I do not understand quite a few of the jokes. Fortunately, they have comments for every single comic which is a required read. Unfortunately, some of the comments go along the line, "I really have no idea that this comic is about". Well, neither do I as a reader.
I also do not agree with their position on some of the issues in gaming. Still, there are some diamonds in the rough, enough of them to warrant 3-star rating.