C-130J Program

Working at a base full of various C-130 versions, I see and hear the Herky Bird a lot. I saw a J model several weeks ago, and recently I got to wondering what the status is on this program. Who all operates the J/J-30 variants, and how many have been built thus far? How many more will be built?

I understand the program had some problems for a while, but have they been ironed out or are there still issues?