Sexyness, weight, accuracy, quiet, new trigger frame.
I couldn't stand being at school the day my DM6 showed up knowing it was at home in a box waiting for me. I opened the box right up, grabbed my tank and about 20 paintballs. Before I do any of that, I open up the gun and change the firing mode to PSP and make the trigger really light. So I'm in my backyard and I gas it up, put the paintballs in and rip it. The 20 paintballs were gone in less than 2 seconds. I only shot at a really skinny tree with it and hit it every shot ball on ball. I went back into my house completely amazed at how well the gun works.
I like the changes Dye has made to the gun. Not only the size and milling on the outside, but to the internals. The board comes stock with three firing modes. Semi-Auto, PSP, and Millenium. Semi-Auto comes stock and it is exactly what it sounds like, one ball per trigger pull. PSP is the setting that ramps the most. It is basically three shots every trigger pull, it's capped at 15 BPS. Millenium ramps a little bit less than PSP. It has short bursts of shots every couple of seconds. I have my gun set on Millenium. PSP is too much of a paint waste for me.
Dye also made the trigger extremely easy to adjust. Just take off one side of the grip and with the turn of your allen key the trigger can be as sensitive and light as you want it.
This is by far the greatest gun I have ever seen. Unlike the DM5, it is ACTUALLY redesigned. It's fast, reliable, light, accurate and sexy. Honestly, what more could you ask of a gun?