...stellar performance as GM.
The most scathing criticism game from the noob-iest player in the group, "The monsters tonight have been kind of anticlimactic." Source: Me running the vampire's regeneration wrong. I forgot to have the vampire continue to regenerate after being reduce to zero hitpoints. The players ended up running away from the scene of the combat after dropping the vampire and I should have had vamp-bbeg get up and come at them again after a few rounds. *Sigh* I'm working on it, I thought that if I had the SRD, the MM, and the module open to vampire powers that I might for once run a monster correctly. There are some GM crutches that I can use that I have resisted on the principle that, "I'm not that bad at running mechanics." I'm past that now and am willing to admit that I am powerless to solve this problem and need help from a higher power (3x5 note cards for every important monster's powers).
Then I ran a tendriculos wrong later. Allowing not only a sleep effect but also a coup de grace against it. [sighs, hangs head, and shakes head]
I have never professed to be a crunch monkey. I'm not bad at the occasional min-maxing (not that I make a habit of it) but remembering all the the things a monster can and can't do and what can and can't effect it based on the type or its qualities is something that seems to get past me on a consistent basis. I'd consider hanging up my D&D-GM-screen if it wasn't for the fact that my group isn't exactly running over with volunteer GMs.
Anyway, I guess I'm not the first GM to have this problem.
I'm hoping that the way I construct this next game takes care of some of these problems.