I don't think it's fair to judge Joe's reign. He's only had it for a month. He really hasn't had time to cement himself as a good or bad champion. I'm waiting at least two more months before rating his reign at all.
Samoa Joe is one of my favorite guys in wrestling. Watching his reign as ROH champion was like watching a Harley Race or Stan Hansen reign. Something really old school, that you almost never see these days, with the exception of John Cena. He just traveled the world, having great matches with everybody. Some of them even legendary, like Punk vs. Joe for instance (first US match in seven years that Dave Meltzer gave five stars). If they book Joe even half as well as ROH did, he could likely be the best champion in TNA history.
So far if there's any reason to dislike Joe's reign it's the booking team. They never seem to fail to make Joe as unlikable as possible. A couple weeks ago he trusted Kurt Angle... again. And Kurt turned on him... again. Then he got back with Nash. I mean why does THE CHAMPION need a mentor? Isn't a mentor supposed to help you get to the title? I was watching Sacrifice last night, and it just made me so angry to see Samoa Joe whining like a schoolgirl, and Nash playing the cool hero.