I have one of these.
I got mine free
. I was at a guy's house, who has gotten into buying these various BB guns; I shot his and was impressed with it, and he gave me one.
It looks almost identical to a "real" Glock 19.
The slide doesn't run, it is fixed in place. Therefore the slide lock also is just for looks.
There is a crossbolt type safety on the trigger.
Other than that, you would have to examine it pretty close to tell that it isn't a "real" Glock 19.
Mine shoots pretty good at 10 yards or so. Probably close to about as good as I can shoot a handgun.
I didn't have any kind of hangups (malfunctions).
The trigger of course leaves a lot to be desired. Glocks typically don't have the best triggers and this one is worse.
But, all in all, I think it is a fun backyard plinker.
I don't really know about it's fitting in a holster: I never tried to holster mine and besides, I use Milt Sparks leather holsters for my carry guns, so I am sure it would fit fine.