Well I've had my copy for a couple of days now and here are some of my impressions;
Art
Grade: A+
Some of the best artwork WotC has produced in contained in this book. I am simply blown away at the jump in quality over previous MMs. There are maybe 5 pieces of art I don't care for in this book (the Ogres, Blackspawn Stalker (although I love the game mechanics) and Greathorn Minotaur amoung them) compared to 15 or more from previous MMs. I even like where the monster pics are placed in the book - right opposite their game stats (although this has been the norm for a while now).
Orginality
Grade B-
Yes there are a lot of templated/classed creatures in this book. The table of contents released a couple of weeks ago will tell you that. So MMIV loses marks on orginality simply because there aren't as many new monsters in the book. What brings this score up from a C- to a B- however is the decision to put in actual new monsters and not rehashes of old 1E & 2E monsters. Things like the Spawn of Tiamat (and yes I love them), Lunar Ravager (a large CE fey!), Inferno Spider, Joystealer (love the picture of this evil fey - creepy!), Whisper Demon, Demonhive, Defacer, Corrupture (ooze resulting from the warping of nature), Briarvex, Clockroach, Clockwork Steed, Verdant Prince etc have evocative backgrounds and interesting abilities. One complaint I do have is in the Spawn of Tiamat specifically the Bluespawn. 2 of them (BS Ambusher and BS Sotrmlizard) look way too much alike for my tastes. Their game stats are different enough but the Ambusher really should have had a more humanoid appearance. So it may not have the greatest number of new monsters but those it does have are really good!
Layout
Grade: A
Very well laid out with everything in a logical order. The new stat block is very easy to get used to (especially with the point by point breakdown given in the introduction) and I loved having any creatures special abilites (ie the Pain ability of the Wrackspawn) right there in the stat block. I am very glad they did away with the Power Attack inclusions ala Hordes of the Abyss - the Attack Options line more than fits the bill for a quick combat reference especially if you, like me, are inclined to forget things like power attack, dodge etc.
Overall
Grade A
This is my favourite MM to date. The 'extras' of the sample lairs, 4 full page colour maps of 'quick' adventure locales, Knowledge (X) checks to find out about a creatures abilities (why this wasn't included in every MM to date I'll never know - it is a very useful inclusion), templated/classed versions of old favourites and the new and imo, exciting Spawn of Tiamat really made this one a must buy for me. The first 'must buy' MM since the first.
