Just recently finished EotB 3 again, with a party imported through the series, and i believe that the last game has a somewhat unjustified bad reputation.
The game may be not as strong as the second one but really who cares, it's still a very gripping dungeon romp.
I liked the athmosphere in the dungeons, it's fittingly grim, especially in the final dungeon. Puzzles are relatively easy, but that's fine, appropriate for the game. The monster ambience sounds add to the somewhat gloomy feeling, i liked the hag laughter. Also the NPCs are interesting and fit into the setting i guess. Being able to attack with melee from the middle ranks is a nice addition.
Myth Drannor proper is kind of lackluster, but that may be intentional, they could have just called those the ruins of anything and nearly nothing would have changed, just some ruins with random monsters. The starting area also isn't the greatest example of good level design, it's a huge place where you can hardly tell where you have to go, and the wilderness level with its labyrinth like mazes... i dunno. Fortunately they aren't too large. Then there are quite a few rooms in the dungeons with nothing really in them, but this isn't necessarily a bad thing, you could say it adds to the realism. The loot you can find was a bit strange sometimes, in one place there are like 4 +1 darts like seemingly just for the sake of it, then somewhere else 4 ordinary rocks and again somewhere else 4 non-magical shields and such (probably placed in those places to be used for pressure plate puzzles nearby, but why when your party carries so much useless stuff around anyway...), and then there are all the +(5-x) weapons you find but you know you won't use...
Overall, quite nice game, would theoretically play this again with a different party, but there are a ton of other older games i haven't tried yet, so i probably won't touch this anytime soon again.