A monster book with solid game mechanics (unlike say... Creature Collection unrevised) that my players have not yet memorized? Sounds lovely. Bring on the variants and other curveballs to confuse any players inclined to use out-of-character knowledge (yeah, players *shouldn't* rely upon out-of-character knowledge, but let's face it, it's preferrable to have genuine lack of knowledge about a monster rather than a player pretending he doesn't know stuff).
WotC's monster book offerings may not be as inspired as the Monsternomicon (my fav d20 monster book) but they are usually very useful and useable - chock full of (usually) mechanically sound monsters. Ironically, the relatively bland nature of WotC's monsters often makes them easier to just add to homebrewed worlds whereas stuff from the Monsternomicon and the Creature Collections often are very particular to their setting.
My copy is due to arrive at my FLGS this week.