This issue has several good points, despite some plot missteps. The missteps are fairly apparent, and don’t need pointing out (Baron Hugo?). The good parts may need some clearing off.
The first good part is that this is the first appearance of another classic FF villain — Diablo. Diablo has yet to make his big mark on the Marvel Universe, despite having more staying power than (groan) The Miracle Man. There may be a hidden Diablo gem in these issues somewhere, but I can’t think of it. We’ll have to see.
The FF are in another interesting environment as well — Transylvania. It’s a fun place for the FF to start a story, and their ‘investigating a haunted castle’ is slightly Scooby-Dooish, they stay there too long, and… Baron Hugo?
The Thing’s character reversal starts out being by-the-numbers, and fairly contrived. The FF are convinced he’s under some mind-control since he ties Reed up. Johnny says he’d “never attack Reed that way, no matter what!” except that he’s always attacking Reed just like that.
However, when Ben comes back to himself and finds he’s been being controlled by Diablo, he goes on one of the most delightfully playful pursuits and ends up resolving the whole story himself. It’s a great moment and communicates real joy from The Thing who is probably the most defined and interesting character so far. We’ve rarely seen just one member of the FF be completely responsible for tying up the story in this way, and to see The Thing do it here is a very welcome change. For its weaknesses, it has great and original moments.