Shooters tend to be a conservative lot. Most shooters, by the time they reach my age, decide that they have discovered The One True Way and proclaim themselves silverbacks of the tribe. They've figured out what's right for them and their circumstances and, by extension, it's right for everybody else, too.
You'll see it in everything: caliber choice, shooting stance, revolver vs. auto, night sights and weapon lights, red dots and lasers, single-points and loop slings. There's never a middle ground, either: veering from The Way will not only get you killed, it will brand you as a Walter Mitty Wannabe SWAT Mall Ninja or a Crusty Old Has-Been, depending on the topic at hand.
It was with some distress then that my original impulse when I saw Magpul's new AFG was "Pphhttt! Silly gizmo," when I clapped eyes on it. That first impulse was the wrong impulse. Like almost any other thing in the firearms world, from speedloaders to night vision optics, the answer to "Is it any good?" is "It depends."
What are you going to use it for?
How are you going to use it?
Have you been trained in its use?
Does it integrate with the rest of your gear?
Does it offer you enough of a concrete improvement to make the expenditure in money and training time worthwhile?
Only one person knows the answer to that question.
I don't know if the potential benefits of this particular gizmo for me would offset the time and training it would take to put it in my toolbox; after all, I've already had to relearn my entire method of using a carbine once in the last decade, and how often am I going to need to use a carbine in real life? There's a reason that the vast majority of my training time gets spent with pistols and revolvers, after all. I'm sure plenty will sell to folks who just want to buy the newest thing to hang on their carbine, without giving a thought to the training or proper implementation aspects of it.
Is it any good? I dunno. It depends.