I own a smoked-body KJW G23.
I owed a KJW P-14 (i.e. double stack 1911~~-ish) prior. I have not handled the non-cansoft version of the KJW G23, so I don't know how much of this is Cansoft and how much is KJW G23.
I love my GBB, for the pricepoint, don't think it can be beat. It's simple, it's a beast, and goes "Pow" when I want it do.
The body is strong, fits together nicely. When it's in your hand, you can't even tell that it's Cansoft, & in holster with the mag in, it looks alot less cansoft. The magazine well backstrap is slightly off dimensional from real glock, so I had to modify a real-steel retention lanyard lanyard to fit in properly, including filing. The body really resisted the filing, so the lanyard plug was modified instead.
The field stripping slide release is a bit annoying as it doesn't slide equally to strip the slide off. (i.e. it tilts to one side or the other, you really have to wrap your hands around this in strange positions).
The slide/recoil spring is pretty light, so it doesn't recoil with quite as realistic 'twack' as I'd like, and it's easier to push the slide out of battery as a consequence.
The gun's trigger safety is missing (i.e. must have finger on the trigger for the striker to fall), I'm told that this is a North America licensing issue.
The Glock master safety (moving the serial number plate back & forth, under the barrel) is annoying, I wish it was 1mm higher so you could lock the gun in safe as easily as the real deal.
The slide does reciprocate on metal rails, so you don't have to worry about wear & tear. (I keep getting asked that question, and always wonder why people would think that KJW would change something just for CanSoft)
Except for some slight scratches in the mag well due to modifying the GBB/Lanyard retention plug, I have no cosmetic wear. I have not attempted the gun at really extended ranges, but works well for standard CQB engagement distances. The gun is not old enough to comment on the magazines (seals and/or mis-feeds).
I would recommend this gun for the price, it's excellent as a backup piece or for CQB distances. The cost of additional magazines makes this extremely attractive if you're trying to see if you like getting close up and personal. The GBB itself is not as noisy as other Glock GBB's, so a suppressor should really help and be surprisingly quite.
I am trying to find speedplates for the magazines, so can't comment on fitment with them on.