Freaking hard to release? Is it only designed to be sling shot? It's not that way on the full sized 22.

I think they're all like that when the gun is new. It takes a little bit to break in.

ALL M&Ps should be sling shooted, it's considered a slide stop NOT a slide release.  You'll find reports of slide stops wearing out prematurely, it's from people Using them as a slide release.  Furthermore on thr 22C, considering the slide is aluminum, I can see where you could damage the slide by using the slide stop as the slide release.

Kinda seen this coming. "Don't do that!"
Actually the M&P22C has a steel insert to prevent this very thing.

I think it's important to utilize both methods when you can. Plus it's fun to rustle jimmies by thumbing something that has serrations on the top.

Choose what works best for you, and train with it.

Food for thought:

When you slam a magazine in, and the slide shuts on a speed reload. Wouldn't it be just as bad? I've had a few thousand rounds through my M&P9 and I haven't noticed any slide wear yet.
I think the whole "it's not meant to be used like that" thing is greatly exaggerated.

Different strokes, for different folks. For the centerfire guns just grab a slide stop assembly incase it wears or breaks. Problem solved.
If OP likes to thumb the lever, I respect that. If you like to slingshot, hey man whatever works for you.

IIRC M&P slide stop's are heat treated. They look a heck of a lot sturdier than say a Glock's small slide stop.

If you read the manual for standard M&Ps and the Shield it says to sling shot, M&P 22 compact manual says it's ok to use as a release, however I would still shy away from it.  Glock slide stops don't seem to break nearly close to the rate of the M&P slide stops.  I love M&Ps and would prefer to use the slide stop as a slide release (as I'd previously done on Glocks without issue), however I now train to sling shot.

As I stated before the full sized M&P 22 made by Walther is easy to release. I was just checking to see if this is normal or a defect for the new compact version made by S&W.
When I say it's hard to release, I mean tear skin hard.

When I had a shield it was the same way.