By 2007, D&D 3E had all the bloat of 2E and then some and was running on fumes. Monster Manual V was the final one for the edition. It never gets as ridiculous as MMIV, but that is probably more from exhaustion than anything else.
Everything in here feels either vaguely familiar or tonally inappropriate for D&D (see the Mockery Drones, demonic centipedes that look like people until threatened, at which point their faux humanoid head explodes and the creatures attack). As evidence that the designers were struggling to fill their page count, a good number of unique NPCs are included within.
Like the Spawn of Tiamat in MMIV, MMV devotes 22 pages to a new type of illithid, the mind flayers of Thoon, a colony corrupted by the forces of the Far Realm. They are physically stronger, involve parasites and crazy automatons and monster generators called madcrafters and generally feel like a half-baked mod for a Starcraft army. I love mind flayers, but come on, they eat brains. The design trade-off for that easy PC killing ability is a frail body. Shooting them up with steroids seems extremely unfair.
Oh, and what is up with those three-headed skull lords? They’d be rad on the cover of a doom metal album, but I feel like if I put them in a game my players would fall out of their seats laughing.
