Neat idea and about time glock got around to this. No first hand experience with the 44 but I have had the M&P 22lr for a while. Same concept and I imagine similar execution. My M&P is a little picky about ammo and inherent accuracy is on par with a 9mm service gun but not as good as my ruger mark 3/4, which shoot any kind of 22lr just fine. My actual favorite 22lr pistol is a 10-shot S&W 617.
Bottom line is I bet the 44 will do a decent job of mimicking glock ergonomics and function which will make it a valuable training tool for glock shooters looking for cheap practice. Unless they come up with some magic, I presume it will have the same ammo sensitivity as my M&P, so you will get plenty of practice clearing malfunctions. As far as a basic 22 side arm for hunting or plinking, I am betting it won’t dethrone the current lead offerings from ruger and others.