I have two of them, a rifle and a pistol. Both have been good shooters and are a good beginners gun and AR experience. My sons girlfriends boys both started out on them and quickly transitioned to actual AR's with no trouble at all.
They are basically a slightly downsized version of the real thing, and are light enough and can be made small enough to fit smaller kids with no troubles.
They are fun to shoot and once I got an earlier version sorted with S&W, the two I have now, have been reliable. Their mags work well, are easy to load, and are trouble free.
The first M&P15-22 I bought I got used and it was part of a recall (issues with bolt dimensions or something) and had issues. It went back to S&W three times, on their dime and they finally just gave me a new rifle. That solved the issue.
If anything gives me pause with them, its the extractor. There are a couple of companies that make aftermarket versions that I think are a better design, and I have replaced those in my guns with one of them, after dealing with, and seeing what went on with the first gun and trying to get it sorted.
The extractor on the first gun was missing when I bought it, and I didn't realize it until I started shooting it and trying to sus things out. I replaced it thinking it would fix things, but it didn't as the issue must have been something else. When I sent it back, it came back with a factory extractor in it, and that too came out while shooting. It hasn't been an issue with the guns Ive replaced the factory extractors with, and I did keep them as spares.
If you get one, Id suggest getting a spare extractor and the associated parts. They arent all that expensive, and it cant hurt to have a spare.