I own a Sub 2000.
Pros:
-Perfect weight/balance for me
-450 rounds so far, no jams of any kind, tried Geco (Dynamit-Nobel) 124 gr, Winchester WB 115gr, American Eagle 124gr and 147gr, all FMJ round nose
-Folding ability lets me use a smaller case, which can make a difference if travel space is an issue
-Light recoil
-Very easy to clean chamber and barrel while folded
-Quad rail is holding up with no issues either (make sure to degrease everything before assembling, I used stronger locktite white/red on all rail screws)
-Decent accuracy, about the same as my stock Ruger 10/22 but much flatter shooting, probably 4-6" groups at 100 yards in my hands
Cons:
-Iron sights are ok for me (peep sight/post style), some people have a hard time craning their necks the right way to line up
-Front sight targeting post sucks durability/reliability wise (the orange plastic piece), I plan to make one out of metal, maybe redo the rear post as well as change the front post screw/nut
-Full disassembly is a pain, lots of parts to watch
-Optics on quad rail need to be removed to allow gun fold up
-Brass pin lock is meh, I use a pull though pad lock to keep it safe locked/folded
-Burning plastic smell for the first couple hundred rounds, smells like normal grease and burnt powder now, no stress fractures or worrisome burn marks though
-Can really ding up ejecting brass if reloading is an issue, no split cases but kind of deformed with various dents and squashes
-Optics on quad rail require either high rings to clear front post or a big objective like that one Tasco red dot (which sights pretty nicely thought the front post loop)
As it is:
Unique gun, cheap to shoot, easy to clean (barrel anyway), more punch than a 22 with better flatness.
So far has killed many dangerous types of fruit and evil soda cans.