I've only had mine out 3 times so far, so I haven't fully formed an opinion of it yet.
Range Trip #1 - Only put about 50 rounds through it on the first trip; had 7 FTE-type failures (stovepipes and double-feeds). VERY accurate. Took gun home and cleaned/oiled it.
Range Trip #2 - HORRIBLE. Every 2nd or 3rd round was a FTE or FTF. A lot of the FTE were cases where it couldn't even START removing the round from the chamber -- had to take a flat-head screwdriver to lever them out. Completely pissed at the gun. Took gun home, stripped it, detail-cleaned everything, and only applied the barest amount of oil in the chamber.
Range Trip #3 - Put about 250 rounds through it. Definitely started off MUCH better than trips #2 and #3; a few FTF/FTE, but not too bad (less than trip #1 as a % of shots fired). VERY accurate. FTF/FTE and accuracy problems got worse as the day went on. Not anywhere near as bad as trip #2, though. Noticed lots of light primer strikes. Near the end of the day, discovered that my top tails (i.e. the one holding my optic!) had come loose. Went home, stripped it, cleaned it, and tightened up all the rail screws with LocTite. Some Googling re: light primer strikes also led me to tighten up and LocTite a bolt inside at the rear.
I'm hoping that tightening up and LocTiting all the screws/bolts will really help. The problems on Trip #2 were definitely caused by over-oiling -- the MK22 really, REALLY doesn't like anything more than the thinnest possible layer you can put on, and ONLY in the chamber. Don't oil anything in the trigger group.
The only other annoyance that I've had so far is the hollow stock -- you get a "ringing" sound with every shot. I actually just (last night) picked up a pack of polyester batting and packed the stock with it. I'm hoping that this fixes that problem.
I'm hoping to bring it out to the range sometime this weekend with all the fixes to see how it runs. I'll post back with updates.