In the past I've had a couple of very good experiences with Mossberg myself. The most recent being that this past Christmas I bought shotguns for both my sons, one came with two modified choke tubes and no full choke tube. Called them and had a full choke via FedEx in 4 business days.
There was one bad experience though. A couple of years ago I picked up a pristine used 500 in 410 with absolutely beautiful wood, very unique. Looked to have never been fired. Had a blast with my sons busting clays with it. Wasn't long and it began suffering light primer strikes, and over a fairly short period of time their frequency increased to about every 3rd or 4th shot. I took the gun apart a few times looking for an obvious problem, even the bolt itself. Finally called them and though by the serial number they said it was built in 98 and well out of warranty, they would be happy to fix it almost certainly free of charge. I carefully wrapped the broken down shotgun which was still unmarred in 3/4 inch foam, packing foam into the blank spaces in an appropriate sized box so that there was zero movement and it was more than adequately protected on all sided and between the pieces. The turn around was quick, maybe 10 days, but when I got it back there are two dings into the wood on the front edge of the pistol grip portion of the stock. They are easily 1/8 to 3/16 deep completely through the finish! OUCH! They stated in writing what they had done to the shotgun which included a completely new bolt and trigger assembly free of charge. Free of cost depends on your perspective when I am staring at the dings and feeling them under my fingers while shooting it. The boys and I took it once again on a clay bird shoot and it suffered once again from a light primer strike on the 5th trigger pull, and the 7th, and the 9th! The problem is now worse than when I sent it in with a new bolt and trigger assembly. I'm not too confident in their CS any longer, though I have 3 other Mossberg shotguns in different configurations currently and have had others in the past without issue. Like I said I even bought two this past Christmas for my sons, but I doubt I'll ever send one back to them again.
In all fairness to them, I did not make a formal complaint about the damage, so they did not have a chance to attempt to right the problem. Perhaps they would have been willing to, but I've never seen wood like this on any Mossberg, and my fear is that what they would replace it with would not even compare.