My initial feeling about this book was less than enthusiastic. "More monsters, more templates, bla bla bla..." After reading that the crystal dragons would be included, I was even more wary, as those monsters had been released as Psionic Handbook Web Enhancements. Was I going to be paying for monsters that were already released for free? After seeing the sneak previews and full monster lists on the WoTC website, I was much more eager. And so when I got to look at this book, I tried my best to keep an open mind.
This is a very good book.
The Introduction
Much more substantive than the first MM introduction. Several pages are dedicated to the actual game design of monsters by type. This information did originally appear in a Dragon magazine, but to have it appear in an "official" publication is quite nice, both for evaluating existing monsters and for the enterprising who wish to make their own.
Also included in the introduction are some other reprinted information that should have been in the MM introduction, such as the Face/Reach table & nonability definitions for attributes.
The Monsters
The learning curve on how to make readable books seems pretty good for WotC. The stat blocks are now formatted with alternating white & tan lines for each section, visibly distinguishing where a monster's attack routine ends and where it's damage description begins. Not only is it easy on the eyes, but it also makes for quicker reference.
Several key game mechanics have been added or adjusted in the display information. A monster's AC entry includes touch & flatfooted AC. (I know this originally appeared in Monsters of Faerun but it's nice to see here) Monsters with Improved Grab or similar abilities now have their grapple check number listed with the ability. (this number being the easiest to mis-calculate and underestimate) Most monsters also include their ECL listing, for players wanting to try something different, which is a number that in retrospect should have been included with almost every monster from the first MM.
There are a large number of higher CR monsters, which is certainly useful for the DM with a long-running campaign. The monsters themselves seem well-balanced, entertaining, and mostly well-thought out, but as the monsters get bigger & bigger, the game mechanics start to get a little odd.
Besides Gem Dragons, other monsters present are re-prints from other sources, including most of the monsters from Masters of the Wild. About 1/3 of the monsters listed are from older versions of the game, taken from the old Fiend Folio, & Monster Manual II. In the case of 3E reprints, this is an irritation, but in the case of older monsters, it's nice to finally have a game tested 3E Banshee. And, since I specifically mentioned them, the Gem Dragons get a very nice treatment in this book, as do most psionic-flavored creatures, with notations making them compatible with a 'standard' 3E game, or balanced when using the Psionics Handbook
Many of the monsters listed are not merely "throw & go" monsters. A ravaging CR 12 monster that kills purely for sport can't be used as a random encounter without damaging the player's suspension of disbelief. Like the 30'x50' dragon in a room with only one 10' x 10' door, the CR 19 monster that's found wandering the forest just doesn't make sense. So while it's nice to have higher CR monsters, this book does require a little more work to integrate it into an ongoing campain. Again, that's less of a flaw of the book, and more of the d20 system.
Templates
This book is more ambitious than the first Monster Manual in terms of it's templates. There are still a few "generic" templates, such as Monster of Legend, Spellstitched, Titanic and Warbeast which are really little more than monster "power-ups". There is a Death Knight template that delivers exactly what older games expect & hope for. The Half Golem templates are another example of something that very strongly lends itself into integration into the game setting versus mere random encounter. The chimeric and tauric templates are very good tools, if a bit tricky to understand, for DMs wanting to put more fantasy in their fantasy games.
Artwork
Much of the artwork is good, some of it very good. Others are less than inspiring, but on the whole, given the very strange nature of some of the monsters, the artwork is more than passing.
The Monster Manual II is roughly the same page count as the first MM, but priced at $29.95. The value remains constant, if not slightly higher. Aside from the combat uses of the monsters presented, many lend themselves to story arcs and/or campaign development, which in and of itself has inherent value.