i've owned my KJ Works 605/G23 for about two weeks now. it is 95% true in dimension to a glock 19, and trade marks aside is hard to differentiate once the orange tip is off. the lower is exact, the slide is approx .5mm wider (measured with my shitty harbor freight micrometer) and fits into most, but not all holsters for a glock 19. it shares some parts with the TM/WE guns but isn't 100% compatible and the info is scarce so do some research. i've found a few US vendors selling parts, the rest come from overseas.
have about 250 rounds through it with little issue. the gun feels, functions and operates like a real glock - takedown is the same, trigger reset just like real steel, last round hold back, etc. expect about 300fps, and pretty darn accurate out of the box at reasonable distances. the green gas/propane mags hold 18 rounds, and you can just about get through two mags worth of ammo with one full gas charge. ymmv based largely on temp and cool-down (warm-up?) period.
plans are to use it for training purposes (have a glock 19 and 26 for work), for sport at the local indoor airsoft places, and to help train my children. i originally planned on using it in my small backyard, but the rounds bounce back HARD, EVERYWHERE, and eye protection is a must. can punch through aluminum beer cans, PVC fence, some glass and plastic so be forewarned - this is not a toy!
i bought mine at a great local place here on long island - PM me for details.