The ideas at the heart of this episode, Troi loosing her empathic sense and the two dimensional beings, both have promise, unfortunately that promise is not realised.
The science behind the two dimensional beings and why they could not be detected is rather weak. If the sensors on the Enterprise are so dependant on how the ship is oriented it is a wonder they can ever detect anything at all. It was a clever premise, rather than going for the more grounded in Physics idea of higher dimensions, that is more commonly used in Science Fiction, they instead went for lower dimensions. This was a good variation but the explanation was just too silly, and yanks the viewer out of the experience. This is however a minor complaint, there have been worse explanations in sci-fi and indeed in this show, that have gone unnoticed. The reason I and others are nitpicking the sci-fi is that the main story is so flawed.
It seems the intention was to show how a character reacts to a debilitating loss, it is however executed very poorly. It is understandable that someone could react angrily and erratically in such a situation, but that is mostly what we get, with very little progression through the stages of grief. Troi comes off as a very unlikeable person, with a superiority complex, I felt little sympathy for her. I know in reality it can take a person a very long time to deal with such a loss, but in TV-shorthand it should have been possible to show more progression back towards the Troi we know and love. The writing is generally weak, it is not only Troi that behaves uncharacteristically. Captain Piccard trotting out the "losing one sense, heightens the others" line did not come across well, neither did his reaction to basically being insulted by Troi.
For a show that normally does a wonderful job of dealing with difficult subjects, this episode is almost a complete failure. The way the episode plays out, Troi does not really show that she would have learned to cope, missing a great teachable moment. Even at the resolution of the episode when her empathic powers are restored, she is so overjoyed with her recovery that she shows no genuine remorse for how she behaved. In the end we are left with a story and character with little to no redeeming value.