My quick thoughts after finishing Dragonborn's main quest:

Par for the course, really. If you like Skyrim, this is essentially just a smaller chunk of that. However, there is enough new content to warrant a look, so while I can't wholeheartedly recommend this dlc on that basis, I certainly give it a thumbs up.

Criteria changes entirely if you were a Morrowind fan. Much of the new content answers questions and reveals new info about what happenned to Morrowind and the Dunmer after the Red Year. Just about everything outside of the main quest is a callback, reference, or incorporates material from Morrowind and its Bloodmoon expansion. If you're a longtime fan, It is definitely worth your money.

So essentially: Not necessary but highly recommended for recent fans or casual gamers, an absolute must for the old Morrowind crowd.

I'm still waiting for the east empire company DLC that lets you play in a small part of akavir to give me that Dutch East Indian Company feel.... I'm pretty sure the next DLC will be more or less focused on the East Empire Company.