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.
Complete Monster: Emperor Palpatine. While his appearance here is very short, he still qualifies thanks to the sequels, and considering that he is truly heinous by the standards in the history.
Director Displacement: As noted on the main page, George Lucas was the executive producer, and neither directed nor wrote the final script for the film. Many critical fans point out how the best Star Wars film had the least input from Lucas.
Ensemble Darkhorse: Boba Fett. He had no more than four lines in the entire series and to this day he is highly regarded as one of the most popular characters in the entire series due to this mysterious character who could get semi-huffy with Darth Vader and live (and, of course, his awesome armor).
Admiral Piett. Originally a one-off character, he was brought back for Jedi thanks to fan requests.
The pilots of Echo Squadron have become quite popular in the EU, especially Wes Jansen and Derek 'Hobbie' Klivian. Not to mention Wedge Antilles, who was already an Ensemble Darkhorse from the first film.
...In hindsight, yes. At the time of its release, the movie was panned for being rather a Genre Shift from A New Hope. It was only after a Genre Shiftback to the original formula (in Return of the Jedi) that everyone realized this film's direction had actually been a better one.
...and with time. When Return of the Jedi premiered, it was widely praised for going back to the adventure feel of the original. In fact for many viewers the second movie started being noticed when the trilogy was released on home video and people began to watch the three in order.
Fridge Brilliance: Why did Lando order the evacuation of Cloud City? Was it only so they could escape the tightening clutches of the Empire while they still could, or was it to make it harder for the Imperial troops to stop the heroes' escape by giving them a chance to slip out amongst the confusion of the general evacuation?
On the main page, someone mentioned this is the only movie where Luke carries a "blade" and a blaster. It also symbolizes the fact that Luke's torn between two worlds: The Rebellion Hero, and the Jedi. When he chooses to take the Jedi route, when fighting Vader, he goes from "blade and blaster" to just using his lightsaber. In A New Hope he mostly used the blaster, and in Return of the Jedi, mostly the lightsaber.
Every time we see Luke training under Yoda, he fails a test:
Looking for a "great warrior," Luke fails to recognize Yoda when they first meet.
Luke ignores Yoda's suggestion to not take any weapons into the cave.
Luke can't conceive of how the Force could lift a heavy X-Wing, and fails
It's a blink-and-you'll-miss-it moment, but Luke actually activates his lightsaber before Vader in the movie's final showdown. It serves as a perfect highlight of his impatience, aggression, and continued flirtations with the dark side.
Fridge Horror: The carbonite facilities that Vader describes as "crude" lack OSHA Compliance because they can. They employees are the small Ughnauts, refugees from the Anoat System, a planetary system that went bankrupt and entered anarchy so horrible that the Empire refuses to touch it because it's just not worth the effort. Plus, the facilities operate outside of any governing body, excusing them from worker protection laws. Lando has the humans who probably have chemistry or business degrees doing the white-collared jobs with comfy office chairs, and the jobless unskilled foreigners who don't speak Basic doing the manual labor without safety precautions. Pretty shady for a place that seems so utopian.
Fridge Logic: The gravity on the asteroid they land on should be incredibly low. When they are in the Falcon, it can be explained as Artificial Gravity, but later they go outside to investigate and the gravity is still normal. Even if it were a large asteroid, for example, Ceres only has 1/36 the gravity of earth.
"Funny Aneurysm" Moment: Before the asteroid chase, Han is trying to repair the Millennium Falcon when his toolbox falls on top of him, hurting him in the process. In June 2014, Harrison Ford got injured during filming for Episode VII when a hydraulic door from the Falcon set fell on top of him.
Hilarious in Hindsight: In an interview soon after this film, Lucas said that many people felt C-3PO was "the worst character ever". Yousa serious, Georgie?
Luke attacks a Wampa in self-defense. A Wampa is reminiscent of a yeti. Skips, the character that Mark Hamill voices in Regular Show, is a yeti.
In Return of the Jedi Leia says "I know. Somehow I've always known." when Luke tells her that she's his sister. So, about that French kiss on Hoth, Leia...
The scene where R2 and Yoda fight over Luke's lamp was made even funnier when the prequels revealed that ESB was not the first time Yoda and R2 had met. It's somewhat comical to think that R2 probably realises that he's dealing with one of the most powerful beings ever to have lived... and decides to continue trolling him anyways.
Memetic Mutation: Luke, I am your father!note Vader: "Obi-Wan never told you what happened to your father." / Luke: "He told me enough! He told me YOU killed him!" / Vader: "No, I am your father."
"Thats not true, that's impossible!"
"I love you." "I Know."
Never tell me the odds!
"Why you stuck up, half-witted, scruffy-looking NERFHERDER!note "WHO'S scruffy-looking?"
"Luke, don't! It's a trap!"note Yep, Leia said it 3 years before Ackbar did.
"I am altering the deal. Pray I do not alter it any further."
Misplaced Accent: The insertion of Temuera Morrison's dub for Boba Fett's lines in the more recent versions for DVD and Blu-Ray. Accents aren't hereditary, they're based on your surrounding environment, and Boba wouldn't sound like his father after a couple of decades of running around the galaxy.
Never Live It Down: Lando betraying Han. note Darth Vader beat Han to the punch of arriving to Cloud City. Lando was left with a Sadistic Choice of either selling out Han or allowing Cloud City and all of it's inhabitants destroyed.
The Problem with Licensed Games: Like with the previous film, averted again, this time with its Atari 2600 game, which was not only pretty complex for a 2600 game, but also is considered one of the best licensed games on the system. Then fast forward to the mid-1990s and the Super Star Wars trilogy games.
Also the arcade game, made using the same graphics, and the same engine as the previous Star Wars game.
Squick: After Return of the Jedi, Leia kissing Luke on the mouth became this. Even though she states in Jedi that she "somehow" she had "always known" that she was Luke's sister, she may or may not have done it to make Han jealous (in which case, that may or may not be an implied Retcon).
Shocking Swerve: At the time, Darth Vader telling Luke that he was his father. It came right out of nowhere and the foreshadowing from the previous movie could have referred to a different kind of father. It worked, nonetheless.
The Wampa was mostly removed because of it in the original version. The Special Edition inserts newly filmed scenes of it.
During the AT-AT battle, the Snowspeeders (and related shots, as per Word of God) were not printed at their full opacity. This is evident in a view from the cockpit. Like the Wampa example, this was eventually fixed.
Luke goes a bit transparent when he falls down the Cloud City shaft.
Tear Jerker: Han's poor tauntaun freezing to death in the first act. Necessary, yes, given that its body saves Han's and Luke's lives — but still heartbreaking.
They Wasted a Perfectly Good Plot: Boba Fett is the only bounty hunter seen after Vader puts a price on Han. It would've been interesting to seem some competition between them for who can capture Solo.
Poor Captain Needa. He clearly knows he's going to die but he tries to apologise in person on the small chance Vader will be merciful and/or take the blame for losing the Falcon (which has more to do with the daringness of Han Solo than any tactical shortcoming on Needa's part) out on him personally rather than the whole ship. (It does not help when we learn, in the EU, that almost his whole family was executed shortly after his death.)
Piett. The newly promoted Admiral is fully aware of his own officers that Vader keeps killing, and the poor guy has this look on his face that screams "Oh god, I'm next." Ironically, Vader lets him live all the way through the movie and well into Return of the Jedi. In fact, when Piett does finally die, Vader has nothing to do with it.
Vindicated by History: The film, while commercially successful, was not as popular as A New Hope when released, and Return of the Jedi was seen as a return to form after this. However, the films then started to be released on home video, and those watching it there started seeing this as better than the other two. Now it's considered the best film not only in the original trilogy, but out of all the Star Wars films in general.