Just got back from a day spend skirmishing with the KRISS. Overall I would say I'm very pleased with its performance throughout the day. I only had one jam resulting from a sticky bolt. If you don't charge the bolt right it could get left in the half position and there isn't a forward assist like on AR15s. This was actually great since it got me thinking about the ergonomic efficiencies of clearing a jam for the KRISS. Performance-wise, simply-put, I was very impressed. KWA did a fanstastic job at regulating equal amounts of gas on each shot, and along side a well tuned hop up, the KRISS shot remarkably straight and accurately, especially considering a barrel length of about 6 inches. The 2-round burst feature was a fun feature and performed as it should each and every time.
On the flip side, there were a few things I noticed that could have been improved. Firstly, the sheer weight of the KRISS is still somewhat a turn off. It weighs almost as much as a full size carbine (if not more) and the weight distribution is canted towards the front. I can see how this would have been great to compensate for recoil on the real steel version, but that said, it is quite a heavy piece to run around with on the field.
Secondly, the sling point (which I heard was an afterthought) is not particularly friendly to the right-hand shooter as it is positioned biased to the left hand side. What ended up happening was that the Kriss would swing around when left hanging on my sling as I transitioned to my secondary (see pic below). To rectify this, I recommend investing into a top rail mounted sling mounting solution like the Magpul RSA. A note on shooting ergonomics with the KRISS: Since the sling mounting point is on the top, when transitioning between shooting hands (with the stock folded out), the stock actually needs to pass under the sling instead of over it (as with most conventional platforms). This may take a little getting used to.
Anyways, a couple more pictures of the KRISS' in action:
EDIT: Note about recoil on the KRISS: There is significant recoil on the KRISS, but not backwards as one would expect, but you can really feel the Super V mechanism working.