I am a relatively new DM, doing it since the launch of 4e, although I’ve played D&D on and off for years. I mostly skipped over the 3.x era, due to both real life getting in the way, and my overall dislike of the system.
4e came along and since I felt like Dm’ing, it was the perfect system for me. Are there things that I wish were different in D&D over the D&D I played when I was younger? Sure, but I’m not going to let that get in the way of sitting around with a bunch of friends and rolling some dice.
As far as homebrew vs. published stuff, I run a mixed campaign, using both types of materials. I try to make published stuff fit the story I’m telling, due to time restraints. I doubt I’d be able to devote too much time to detailing and crafting a fully homebrew setting and adventures at this point in my life.
I also run a small D&D blog at http://www.newbiedm.com chronicling my experiences on the DM side of the screen.