Author T. L. Taylor is an academic with MUD and MMORPG experience. This is important, because Taylor examines how real life and gaming interact in Play Between Worlds, using EverQuest as her primary source. Through interviews with players and her own experience, Taylor fleshes out what it means to "live" in EverQuest and outside of it, identifying a gaming culture that permeates both membranes. In some cases, there's not much of a membrane at all, as when EverQuest players dress up as their characters at gaming conventions.
Taylor's book is filled with gaming jargon with little explanation. This book is written for people who understand MMORPGs and EverQuest in particular, which unfortunately limits its audience somewhat. That's a shame, because buried in the exposition of gnomes and necromancers are some important revelations.
A large section of the book is devoted to gender issues. Taylor's female gender matters, both in her approach to EverQuest and the roles she chooses to play within it. The hypersexualization of female characters is a real problem in fantasy gaming and it's what led Taylor to pick the unsexy gnome racial archetype.
Taylor also defends "roll-players." She rails against the stereotype of Achiever-style players as incompetent, unintelligent, and aggressive. Taylor takes pains to show how this archetype is unfounded and that achievers are actually highly competent, organized, and bright. What Taylor doesn't address is that this play style is destructive to other play styles. It's not that achievement-oriented players are bad for games - indeed, Taylor stresses that they actually improve games by breaking them - but that other less goal-oriented players are driven away by their dominance.
Taylor comes to a conclusion that is perhaps not surprising given her experience with MUDs: many of massive multiplayers' problems stem from their sheer size. She's absolutely right; the Dungeons & Dragons'-style of leveling up and killing monsters was never really structured for millions of players killing millions of monsters, leveling up infinitely.
I was ready to dislike Play Between Worlds, but Taylor's conclusion matched up with my own decade of experience with online multiplayer games. Worth reading if you're interested in how MUDs and MMORPGs compare or EverQuest. Those with broader interests in virtual communities or gaming in general will find it a little too narrowly focused.