Some comments on mine:
-It's a fun gun to shoot! A real attention getter at the range too.
-Will fire most all ammo just fine. The only brand I ever had any trouble with was Winchester and I'm fairly certain it was a couple of faulty rounds rather than the firearm. Mine will even cycle on CCI Quiet, but HV is recommended.
-I had not heard of the extractor problems before. Mine must be good as the spent casings want to fly into the next county, especially when firing more powerful rounds like CCI Stingers and Velocitors.
-Cleaning presents a slight challenge as to clean the bore, one has to start back where the stock attaches and feed from there. The feed ramp by its shape offers a bit of a challenge due to its shape and access. Not too hard mind you, just take your time.
-On mine the fake flash hider is a screw on part. Should be trivial to get an adapter for a suppressor if you live somewhere that allows them. (I live in Illinois, so no go for me.)

-Stermgewehre on Youtube did a good review:
He had a bit of a problem getting the bolt to release after a last round hold open. I have found that if you pull and release the charging handle with some authority and have a loaded magazine inserted, the problem is non-existent.
-Regarding magazines, if you get one that is "sticky" in that the follower doesn't move smoothly, take it apart and clean and lube it. Of the 5 mags I have, 2 had the trouble and cleaning them fixed it. Another symptom is that they won't accept the full 25 rounds. Also fixed by a clean/lube.
Like some others, this is one that I will never sell. It's as close to the real thing as I'll ever get.