The 15-22 will not interchange upper or lower with an AR. It is lighter in weight. If it is considered a toy, than it is an accurate and fun toy.
I believe S&W's intent was to designed a .22 cal rifle that performs with accuracy that has a platform to add all the AR goodies.
Cleaned last night, shot some more again yesterday. I'm now up to 1000 rounds, no misfeeds or misfires, or problems. I shot some old 22's in it that you could hear the difference in shells(pop-bang-light pop). My buddies couldn't believe the gun functioned perfectly and accurately with these rounds. It eats what you feed it.
629man