I can not answer as to how good the shotgun is. I have only held one about 3 times and have never actually fired it. Dont get me started on the handgun tho! Now THAT is a NICE piece of work!
As for your question about magazines (clips) they are indeed readily available according to John Jardine.
I've used it several times before, and it suited me fine. Accurate with slugs to 50 yards (longest distance I used it), and had no feeding problems or any other problems with it.