Short trigger pull, light weight, pretty darn quiet
None that I can think of
I bought my J2 last weekend and couldn't wait to take it out today and have some fun with it. I needed to re-time it due to the 30 degree weather, but that was expected. The J2 ripped all day and was too much fun to shoot. The accuracy with the Empire barrel was great and the CCM bolt was awesome. I had excellent efficiency, too.
The gun is perfect, right from the jump. Other players, a lot of them, commented on how great it looked and one guy traded his Shocktech with eBlade for one game and he really liked the CCM.
If you want to stick with a mechanical gun, this one rocks. I could easily outshoot my 10-12 ball revy with y-board, which impressed a lot of people including myself.
Great gun and if I didn't already own one, I'd go buy one.