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.
Since the opening of the game blatantly contradicts the ending of the previous game, and that the Avatar had not been to Earth since the start of Ultima VII, maybe the Time Lord unwittingly called upon some random guy who had moved in to the Avatar's house after he had been missing for years in Earth time?
Ending Aversion — Many Ultima fans regard this as a pretty terrible way to end the series.
Particularly notable is the description on The Spoony Experiment as "one of the most bungled endings to an epic story in the history of fiction."
Memetic Mutation: "What's a paladin?", mostly thanks to Spoony. For reference, it's referring to the fact that the Avatar has to be told what a paladin is. This is despite the fact that Sir Dupre, the Avatar's Lancer, devoted companion, and closest friend since Ultima IVwho had previously made a Heroic Sacrifice so the Avatar wouldn't have to... was a paladin. Furthermore, at the beginning of the game you can even choose to be a paladin yourself!
Most Annoying Sound — The Avatar randomly whistles. The Avatar randomly coughs. Even turning the voices off doesn't make it go away.
What Could Have Been: Before it got behind schedule, Ultima IX had good graphics for the time. In addition, Richard Garriot originally intended the origin of the Guardian to be completely different - rather than being The Avatar's dark aspect, he would have been the three Shadowlords combined into one entity. Interestingly, this would have tied this back to the first game far better- the Shadowlords were created from the shards of Mondain's gem, a plot point in Ultima I. Mondain and his influence remained extremely important figures throughout the series- Big Bad in game one, his girlfriend was the big bad in Ultima II, his son in Ultima III, and the shards of his gems formed the Shadowlords in V. And he has influence over the Gargoyles' religion in Ultima VI. Having something related to Mondain would have been a perfect way to end the series.
Villain Decay — The Guardian, previously an unknown demonic force, is revealed here to be the darker aspect of the Avatar himself, expunged from him when he went through the Quest of the Avatar in Ultima IV.