I love mine, I have about 2,000 rounds through it and it has only had about 5-7 FTF's, which were bum rounds, as they wouldn't fire when re-striked either. I have about 6 S&W mags for it and 3 ProMag 32 rounders. The ProMags are great mags as well, they feel and look like the same quality as the S&W's.
One thing to be sure of is to load the .22's one by one allowing the follower to hold them up as you go, just use your finger to take the tension off the round to get the next one in. Don't try and pull the follower all the way to the bottom and drop the .22's in, they won't line up right and you will have trouble feeding.
I had heard but have not confirmed that ProMag makes the S&W mags for S&W. Can anyone confirm or deny this?