I joined the forum a few days ago. I've been using single DIN Pioneer head units for more than a decade now and got an AVH-4100NEX as my first foray into double DIN and Pioneer's NEX line. So far I LOVE it. It's certainly not without it's quirks but I do love the ease of use, 13 band EQ, and how great it sounds matched with the speakers I'm running (in my signature). Plus the backup camera is grand.
I'm an audio engineer by trade and love a great sounding system that isn't overdone.