I know the BAD DM trap. The first module I ran was a lot of fun--the good guys succeeded, had a fun battle, and totally foiled the well-laid plans of the bad guys. Up until the moment when the bad guy sneaked away and succeeded anyways. As a DM, I really wanted the bad guy to win. I'd seen too many movies where, after the "final scene," the camera zooms into the hockey mask, and the eyes flick open just before the blackout.
Even when the good guys win, these movies tell me, it's scary/cool when the bad guys weren't really defeated after all!!!. I accepted this as good storytelling, not as the cheap marketing ploy that it actually is.
At any rate, that first module ended with a bunch of really pissed off players. I'll never forget that. I was frustrated, angry, and confused as to why they were mad. I mean, I had fun. What's the big deal?
It took me a long time to realize that what's fun as a DM (screw...I mean, challenging PC's) isn't necessarily fun as a player. I would ask your DM to brainstorm 20 of the best games and most fun experiences as a player. Then have your whole group do that. Turn them into the DM, and tell him "This is the game we want you to run!"
What does it take to be a good DM? Depends on what you mean by 'good'. A fun DM is one who knows his players, and can come up with exciting and intriguing scenes that will engage everyone in the group. A powerful DM is one who can create complex moral, political, and emotional scenes that the players will never forget. An epic DM is one whose stories are so huge, so fantastic, that they rival mythologies.
Not that I'm trying to spread around the flattery...but from the one session I got to play with him, I think PirateCat is the best DM in the world. Literally. You want to know what it takes to be a DM, insinuate yourself into one of his games at the next con you attend.
Spider