Unlike most fans, I'm not crazy about the character of Barclay. Aside from having a lower level of competence than his crewmates, I never understood what made him particularly noteworthy and I don't think the writers did either. That said, Dwight Schultz portrays him with a certain goofy charm that makes up for the character's limitations.
This one is about Barclay conquering his fears. The scifi premise is frankly uninteresting and doesn't really make sense, but when Schultz is doing his thing, it makes the whole thing bearable. There's also a nice assist from Colm Meaney, who provides plenty of his no-nonsense O'Brien.
Not a great episode, but TNG had far worse.