Great Kit at great price
I am a working club drummer (classic rock covers). I have been using the Roland TDKP, and while it has features I like (ease of portability), I could never quite get the sound I wanted out of it. I purchased the DTX400K, and if you are looking for a great sounding kit at an extremely reasonable price, this is the one. The attack and presence of the drum sounds (particularly the snare) is excellent. It took no time at all to be comfortable with the beaterless foot pedal. The action is very good.The drum pads are sensitive to how hard you strike them, and you can get nice accents. So far, the hardware and attachments seem sturdy enough. Time will tell how they hold up to the road, but if you are not transporting the kit often, they should last forever.
One cool feature is that you can download a free Yamaha app to your iphone or ipad (not to an Android device), and hook the control panel to your phone. While you don't need to do this to do sound and kit editing, having this visual makes it MUCH easier to do so, as there is no LED panel on the DTX400K control panel. It must be noted, however, that the cable that is need to connect the head to your phone does NOT come with the kit. You need to purchase that separately (about $79).
Overall, I would say that this a terrific value - made well, with a great range of sounds. From my experience with Yamaha, it is pretty much what you'd expect from them.