Aside from "1001001", this is the first episode to focus on Riker's character. (I suppose I should include that lame "Hide and Q" episode in season 1.) In a lot of ways, this is where the character of Riker (as we know him for the rest of the series) was born.
It's also the second Klingon episode in TNG, after "Heart of Glory" in season 1; unlike most of its successors, it is unusual because (A) it doesn't feature Worf and (B) it adds some humor and avoids the extreme seriousness of its successors. (Riker himself nods to this when he evinces surprise that Klingons laugh - perhaps we see too much of Worf.)
The story with Riker aboard the Klingon ship is quite enjoyable and on its own would be worthy of a higher rating. Riker's final dinner on the Enterprise, with Picard and Pulaski gagging at the Klingon food, is a hoot. And the twist at the end (I won't spoil it) as Riker saves the day is pretty clever.
However, the B-plot, with the alien ensign struggling to fit in aboard the Enterprise, is largely a waste of time and is something of a drag on the episode.