If you're OK with spoilers for games you may or may not have played yet, you may want to check out this new editorial on Rock, Paper, Shotgun, where several of their editors have stated their opinions on the strengths and weaknesses present in various game endings. The conclusions in Borderlands, The Elder Scrolls III: Morrowind, and System Shock 2 are all pondered:
In one sense, Morrowind has an awesome ending. You spend the entire game circling the forboding, walled-off mountain range in the centre of the map, knowing that it holds a great evil. You visit everywhere else on the island, meeting people, having adventures, becoming stronger, always with the shadow of Red Mountain in the background, so when the time finally comes to enter the area through the enormous Ghostgate it's literally the most dramatic thing in the world.
This top-quality start crumbles into mediocrity the moment you descend into Dagoth Ur's dungeon. It's not just that you've spent the entire game clearing out dungeons just like this one. It's not just that when you find Dagoth Ur he's ordinary-looking and busy writhing like a private dancer. It's not just that the fight with him can be a total cakewalk depending on your character's level.
To me, it was that when you do defeat him, you get a brief cutscene where you're told (You no longer bear the burden of prophecy. You are free.) But mechanically, Morrowind always let you be free. Similarly, you're told that (The sun's golden honey gilds the land,) but the island of Morrowind is unchanged. The Blight plague that hasn't bothered you in dozens of hours is gone, and the ghost fence around an area you'll never be coming back to is gone, but that's it. You walk out of Red Mountain's front door feeling used.