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.
Adaptation Displacement: After the cancellation of the cartoon series, the Movie, which was widely available on home video, became most people's introduction to the Transformers universe.note At least in the U.S. Outside the States, it's the other way around.
Alternative Character Interpretation: Optimus Prime riding into the ravaged Autobot City and blasting the ever loving crap out of every Decepticon in his way. Then, proceeding to beat Megatron to a pulp, even after Megatron shoots him critically enough to wound him. Prime still manages to deliver one last punch so devastating that it practically leaves Megatron crippled. Just Prime being Crazy Awesome, Prime finally doing what needed to be done, or Prime going on a Roaring Rampage of Revenge? He did declare, after all, that Megatron had to be stopped, "No matter the cost."
Awesome Art: Probably the best aspect of the whole movie. The animation is very fluid, with some great dynamic camera angles and exciting action sequences, and the backgrounds are utterly gorgeous paintings. When you consider that the scenery and characters consist primarily of complicated, hard-to-animate machinery, it's even more impressive!
Awesome Music: Every piece of music in the movie is either loaded with synthesizers, or an epic hair metal tune. Everything awesome about The Eighties in one soundtrack!
Special mention to Stan Bush's tracks, "Dare" and "The Touch".
Hot Rod/Rodimus Prime as well, since he ended up having the thankless task of replacing the much beloved Optimus Prime.
Big Lipped Alligator Moment: The Junkions' dance with the Autobots on a Junk planet, to the tune of "Weird Al" Yankovic's 'Dare to Be Stupid' is probably a borderline case of this. The only thing keeping it from being such is Ultra Magnus being rebuilt during the scene, though as that comes after Wreck-Gar settles everyone down from the dancing number...
A random Junkion kissing Grimlock during the dancing number.
Fandom Rivalry: With the Michael Bay movies. There are those who support this movie due to nostalgia and due to it lacking many of the commonly criticized aspects of the Bay movies, while there are those who support the Bay movies due to their more "adult" (albeit immature) nature, their Visual Effects of Awesome, and the G1 movie's much lower budget and narrower appeal. Not helping things is that both versions are disliked by critics on Rotten Tomatoes (the G1 movie has a slightly lower rating than the first Bay movie and a higher rating than the sequels).
Growing the Beard: Though still So Bad, It's Good, this film and the Marvel comics that were running at the time were the point where Transformers fiction started becoming more than just a glorified toy commercial and developed actual plot. Fitting, considering the fact that this film indirectly establishes a lot of the mythos for the franchise that later incarnations would build off of.
He's Just Hiding: Many fans believe that those who weren't killed on-screen survived. One commonly cited example is Brawn, who went down with only a single shot to his shoulder. The fact that even after going down, he was on a shuttle with Decepticons for a lengthy period of time doesn't bode well for him.
This movie is often foremost in the minds of people who said Michael Bay was raping their childhoods by including a prominent human character and a goofy robot buddy. Of course, if you actually watch the movie, there Daniel and Wheelie are...
People made jokes about Orson Welles last role would be a planet.In this flim is his last role ,and he is a planet.
It Was His Sled: Hot Rod becomes Rodimus Prime. Optimus Prime (and several other Autobots) dies. Megatron gets reformatted into Galvatron. The giant planet Unicron has a robot mode!
Narm: The opening scene with Unicron devouring an entire planet is chilling, but when we see a masher within Unicron making cartoony chomping noises, it loses some of its punch.
Never Live It Down: Ultra Magnus' "I can't deal with that now!" in response to seeing Hot Rod and Kup get shot down has become popular in the fandom to make him look like an incompetent fool/ massive Jerkass.
The Scrappy: Wheelie (because he speaks in rhymes) and Hot Rod (his actions - unintentionally - got Optimus killed).
Transformers The Movie was the first Western animated feature film to rely on ideas from anime and comics (and yeah, Star Wars) to set up an elaborate space opera with a backstory and continuity tie-ins to resulting episodes of the series. After it came out, all the other Saturday Morning TV series copied the idea. With the rise in popularity of anime and elaborately plotted multiverse continuities in every franchise (Transformers or otherwise), it's considered no big deal now.
Tear Jerker: Optimus Prime's death scene when he passes on the Matrix to Ultra Magnus, and then his normally red white and blue self goes black as his "spark" finally burns out, leaving Daniel in tears and the other Autobots visibly grief stricken. As if the deaths of all the other familiar Autobots wasn't bad enough, countless children who were fans of the show were heartbroken by the death of the heroic Optimus Prime (and rightly or wrongly, held a grudge against Hot Rod/Rodimus Prime, his replacement), so much so that they had to be escorted out of the theaters by their parents, who in turn were not happy with the film killing off such a beloved fictional robot just to sell new toys. There were even reports that one child locked himself in his room for a week and wouldn't come out because he was still mourning for the deceased Prime. Even if you watch the film with the knowledge that Prime eventually comes back, his death scene is still very hard to watch.
They Wasted a Perfectly Good Character: Inverted with regards to Ultra Magnus when he's destroyed. After Magnus is brought back to life, he doesn't do much and the Matrix is passed on to Hot Rod. He could have stayed dead and it wouldn't have made a difference.