These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Awesome Music: Nothing less than the title music. For a game as epically large as Morrowind is, the music is suitably awesome. Considering who wrote it, it's not surprising that it turns the awesome of the game way, way up.
Crazy Awesome: Divayth Fyr is considered this by most Morrowind fans, due to him being a 4,000 year old wizard, collector of Dwemer artifacts, and slightly crazy genius who surrounds himself with opposite-sex clone wife/daughters, diseased zombie-esque maniacs and the last living dwarf.
Ensemble Darkhorse: Jiub. His badass appearance, the fact that he is the first character players encounter, the fact that he is a fellow prison-ship prisoner along with the player, and his friendliness all make him very popular with fans, despite only having a few lines before being put on a boat. There are a few mods that bring him back and add quests centered around him.
And in Dawnguard, he returns in person! The player can encounter Jiub while wandering the Soul Cairn, where soul trapped individuals eventually end up; as it turns out, Jiub was in Kvatch just in time for the Oblivion Crisis, and his soul was captured by an invading dremora. Although initially somewhat oblivious to his true fate, he asks the player to collect pages from the first part of his epic twenty-six volume Opus, The Rise and Fall of Saint Jiub the Eradicator Hero of Morrowind and Savior of the Dunmer.
Game Breaker: Players can brew potions. These potions are more effective depending on how high the player's Intelligence stat is. However it is possible to brew Intelligence-enhancing potions with dirt-common ingredients. The Intelligence buff you get from that can then be used to brew even more powerful Intelligence potions, which can be used to brew yet more powerful Intelligence-enhancing potions. This can go on as long as you have enough ingredients (and as noted, the ingredients are very common.) When your Intelligence stat has reached the desired level of godliness, go ahead and brew whatever over-powered mega-potions you want—from Restore Health 9999 Points on Self for 9999999 seconds to 100% Sanctuary on self for 999999 seconds to Immunity to Magicka/Frost/Fire/Shock/Poison/Normal Weapons on Self for 99999 seconds. Creating a potion of Fortify Agility will mean enemies will always miss and you will always hit, although you can still be hit by magic.
Also, the Corprus Disease. The effects of the disease boost your strength and endurance, but drains a host of other attributes. Both gains and losses from this are cumulative over time, meaning that if you go to sleep for a year, you'll have 0 in the drained attributes, but a strength and endurance in the hundreds. When you finish the relevant quest, only the drain is removed.
Fridge Horror: The in-game explanation for the lack of character schedules is that one of the early symptoms of the corpus disease is insomnia. This means that everyone on Vvardenfell is infected, and with Tribunal it's spread to the mainland (despite the travel ban) and with Bloodmoon it's already spread to Solstheim, so perhaps even Skyrim is endangered.
Goddamned Bats: Cliff racers, perhaps the most annoying foes in video game history. They make an irritating sound, do little damage, make you flinch when they hit you, drop crappy loot, and come in flocks of three to ten. And once they see you, they won't stop following you unless they get stuck in a tree. They haven't figured out doorknobs, but if you go in a door with some following you, they'll be waiting for you when you come back out. And since they fly, they can swoop down to annoy you from any angle. And their hit detection leaves a lot to be desired.
To make matters worse, they're also very capable of infecting the player with a disease.
Good Bad Bugs: Some of the Ash creatures have vigorous running animations, but the creatures actually move slowly. This leads to an effect that looks like slow-motion running, a la Baywatch.
It's Popular, Now It Sucks: Prior to Oblivion coming out, it was Morrowind that was considered to be "the symbol of all the bad trends in the industry". And mostly for the alleged reason of "dumbing down" for console players. Ironically since then, it is now considered the last good Elder Scrolls game by the same crowd.
It Was His Sled: Is there anyone who doesn't know that the player is the reincarnation of Nerevar these days?
Most Annoying Sound: The guards at Vivec are watching you, scum, and will remind you of the fact whenever you're within hearing distance.
When you're escorting the wisewoman..."hey, wait for me. Hey, wait for me. Hey, wait for me. Hey, wait for me. Hey, wait for me. Hey, wait for me! hey, wait for me!" This easily puts her on the same level as the guards shouting "HALT! HALT! HALT! HALT! HALT! HALT!" in Daggerfall....
YOU N'WAH! FILTHY S'WIT! DIE, FETCHER!
Nostalgia Filter: For most of the current Elder Scrolls fanbase, this was their first game in the series, and as such, it tends to be held up as the gold standard of the entire franchise. Roughly more than half of the criticisms leveled at Oblivion and Skyrim boil down to "it's not like Morrowind."
Padding: If you don't console command your Athletics skill up really high or warp yourself to any town you'll need to go to, you'll spend a lot of time walking. It doesn't help that the default walking speed without very high athletics is slower than an arthritic senior with a walker.
Rooting for the Empire: Some fans see Dagoth Ur as a misunderstood good guy who just wants to free his people from the exploitative foreign Empire. It helps that a huge chunk of his backstory is about how he was betrayed by his supposedly-good best friend.
Mind you, this was after Dagoth decided he wanted to use the artifacts of doom he and Nerevar initially set out to the destroy for personal power.
Alternate Character Interpretation has a big part in this. To some people, the Tribunal murdered Nerevar, and in a later work Vivec sort-of confessed to the crime, while Dagoth Ur was actually just trying to help.
Rooting for Almalexia is a whole another case, rarer but still happens.
Surprisingly Improved Sequel: Tribunal met poor critical response because it was largely a dungeon crawl in an open world exploration based game (though it does add some much needed scripting functions for mods). Bloodmoon instead ops to add a new island to explore.
Squick: The silt strider is a gigantic arthropod used as a means of public transport throughout Vvardenfell. A bit odd so far, but not too out of place for the setting. However, in order to allow for passengers, cargo, and of course the driver, parts of the creature's shell are hollowed out. The driver then controls the strider by DIRECTLY MANIPULATING THE CREATURE'S INTERNAL ORGANS.
Everything dear old Uncle Crassis says, sweetie.
That One Boss: Gaenor. He reflects almost all damage from magic spells and mundane weapons due to having an insanely high leveled Luck. And no, there is not a puzzle to get around it. You just have to have a hell of a lot of Hit Points while you pummel this heavily-armored highly-agile guy until he falls over and dies. He starts as an NPC, but if you speak to him for any reason, he'll eventually come back in armor. Fortunately, he's still easy to avoid. Like most of the annoying parts of Morrowind, he appears in Tribunal.
This is a case of When All You Have Is a Hammer. It's actually relatively easy to beat him by using a weapon with a Damage Attribute enchantment that wipes out his strength or luck (remember, Damage Attribute is the one that's permanent without a blessing from a shrine). However the most often used course (levitating out of range and blitzing him with a ranged weapon or spell) is unavailable due to Tribunal's stupid ban on levitation.
The final boss of the Imperial Legion questline counts as well, mainly because he uses both an Infinity+1 Sword and Infinity Plus One Armor.
** Another is acquiring Eltonbrand. First, it requires you to acquire Goldbrand as part of an obscure quest that you are extremely unlikely to find on your own. (The one person in the game who tells you about it isn't exactly trustworthy and even then, his directions are bad, leading you to swimming around in the ocean further south than you need to.) Then, you get directions from Boethiah to find him/her (it's complicated) a sculptor to rebuild his/her shrine. If you manage to do that, then wait the two in-game weeks required for the statue to be built, you can finally claim Goldbrand. To upgrade it into Eltonbrand, you need to become a vampire (something most players of the game may not even realize is in the game for many, many hours) and perform a specific quest with a specific amount of gold in your inventory. THEN you get Eltonbrand. Complicated and near impossible to find on your own, but very worth it.
Uncanny Valley: In audio form. In various Sixth House enclaves, shrines, and lairs there's a set of bells that they player can ring. There's only half a note difference -instead of the intuitive whole note- so something sounds wrong and unsettling about the noise they produce.
Argonians and Khajiits walk like they broke their ankles. Everyone else walks like they have a stick up their ass (a pretty blazin' stick, though). Their jaws flap in a really weird way when they talk...