I personally disliked the episode in the context of the series as it was never mentioned again and in the very next few episodes he is 100% normal. Unlike shows like Babylon 5, star trek has always had this problem and its terribly annoying.
The episode it self is very interesting and well handled, it just in the greater context it exposes the flaws of the writing crew and the shows continuity, and for that it is a "Bad" episode as it serves to detract from the series instead of play to its strengths.
Eh. I disagree. It's more likely that the writers felt that they had nothing more to say on the subject (or didn't know what else to do with it). The episode itself took place over several weeks, and he was going to see the psychologist beyond the episode's ending. The next few episodes, "Shattered Mirror" and "For the Cause" had nothing to do with him.
In another episode, "Honor Among Thieves," O'Brien is responsible for a man getting himself killed. He takes the man's cat to take care of and you see that even in "What You Leave Behind," and O'Brien checks up on the man's wife in an episode in S7.
It was only when DS9 started copying B5 that it became good.
DS9 never copied Babylon 5. Ira Behr always wanted to take the show into a darker, more serialized format, and when he became executive producer, it's what he did. If you read DS9: Companion, it's pretty clear that the writers never paid attention to B5, and they were just doing their own thing.