I dunno what the other posters are talking about, MMIII is great IMO. I've used a bunch of monsters from it and plan to use many more (Skullcrusher Ogres, Lifeleech Otyughs, Chraal, Death Giant, Chilling Fog, Snowflake Ooze, War Troll, etc.).
Errata? Sorry, that's a pretty weak argument. The monsters work fine. If you really want to be anal about it and make sure every little comma is in place and t crossed, then there's already errata compilations that will let you do so with ease.
Don't let a few naysayers with really big chips on their shoulders ruin what is otherwise a very good book.