I searched for 15-22 and it came back with no results. Not sure if it's not working or if it's user error, but I will post my experience.
I bought a M&P15-22 this past weekend and took it straight to the range. I had an economy box of Federal ammo and started shooting away. I love the feel of the gun. The action is smooth. No problems with the trigger. Sights are extremely accurate. The only issue I had was that my cartridges started nose diving in the magazine and I would get a FTF about 1 round per magazine load. I sent an e-mail to S&W with pictures of the problem and they replied immediately stating that they will be sending me a new magazine, so I'm happy. Overall, this is a great gun for the money.
take a look @ smith-wessonforum.com. There are a TON of threads (good & bad) about them. Looks like the issues with feeding and cycling of ammunition have been taken care of by S&W.
One of the regulars at Eagle Creek had one this past weekend. He was shooting a bulk pack of remington 550ct ammo. He let me run a mag throught the gun.
I found that it was accurate and handled well.
Him and his wife shot the 550ct box minus the duds and I asked if it fed/jammed at all. he said it did not and the only problems were duds, but that is expected with crappy ammo.
I've put in he neighborhood of 2000 rounds through mine with very few problems. As with any .22, it can be ammo finicky and my rifle seems to like the Federal brand best. I think its a lot of fun to shoot and is dead-eye accurate.
I was amazed at how light it was. Scutter and I went to the Tipton Gun show today. They had one and I picked it up. It's a possibility that this one may need to make it in our inventory.