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.
YMMV: Spider-Man 3
Contested Sequel: One of the most definitive examples of the trope. It became the highest-grossing Spider-Man movie, but still earned lots of dissers, particularly among the fanbase. Critics considered it a blatant case of sequelitis, but overall reaction was mixed-to-positive. In general, most can agree it's the weakest installment of the trilogy, but the divide lies in whether or not it's because the quality is actually "bad."
The games were no better either, considering they were made to tie in with this film just like the previous 2. Unlike Spider-Man 2, the games has a ridiculous amounts of Press X to Not Die to an infuriating degree, especially the unforgiving final boss fight.
For a genuine example, while this movie isn't fondly remembered, Thomas Haden Church's performance as the Sandman has still been widely praised and cited as the best part of the movie. That he looks exactly like the comic book character helps.
Family-Unfriendly Aesop: One of the recurring criticisms of Raimi's trilogy was not capturing the humor of Peter as Spider-Man - favoring slapstick sight gags and prat falls over witty one liners (strange considering the memorable quips of Raimi's Army of Darkness) - nor capturing the way he gained confidence from his experiences as Spider-Man in his daily life, which the comics highlighted for years (when not showing how much his life sucked). By the time Peter finally starts to come out of his shell and show some confidence, complete with quipping, in this film it is treated negatively (even before he gets the evil suit), which almost seems to say "Don't grow up, don't take pride in your accomplishments, always remain the shy, mumbling, all-American apple pie-eating boy next door."
Much of the tension could have been relieved if Mary-Jane just asked Peter "You do realize my role in the play was replaced, right?" Or if Peter would have taken a deep breath and talked things through with her after "killing" Harry. On the other hand, he was under the effects of the evil suit, but it felt like he forgot her entirely after getting his revenge.
Don't forget the admittedly in-movie (but treading actual What an Idiot territory) stupidity of, on a whim, publicly giving an open-mouthed kiss to his lab partner at the same time he was still going steady with Mary-Jane. "Special kiss" in and of itself or not, and not even going into fidelity issues, it doesn't take a sociologist to realize that that is going to raise some hackles.
Harry gets his memory back, and then threatens Mary Jane, telling her that he would hurt Peter unless she breaks up with him. Both Harry and Mary Jane somehow forget that Peter is just as strong as Harry, and has had far more experience dealing with superpowered people than Harry ever has. Mary Jane proceeds to break up with Peter, and forgets to tell him that Harry got his memory back, is once again dangerous, and that he threatened her.
Harry's butler tells Harry that Peter did not intentionally kill his father. Either the truth about Harry's father's death slipped his mind for several years, or the writers retro-actively made the butler an idiot to advance the plot, and make Harry and Peter friends again. (Word of God is that the butler in that particular scene is a hallucination, meant to parallel Harry's previous Norman Osborn hallucinations.)
Scientists detect extra mass in their experiment (which has to take place in a pit open to the environment for some odd reason), but rather than actually go check, they assume it's a bird (what 200 lb bird are we talking about, exactly?) and keep going with the experiment. And what if it really was a bird? That would completely change the conditions of the experiment, which is supposed to be with sand, not with sand and the corpse of a bird.
Not to mention that Sandman, a man with ability to easily move an infinite amount of sand, decides that the best way for him to make money with his abilities is to be a criminal. It's not as if there are places with tons and tons of sand that need moving, perhaps to access a valuable resource of some kind.
Outbidding the guys who created the World Archipelago by a few million dollars would've netted him in excess of several billion. Even if we presume that such uses would be too boring for him, and he wants to be where he can hurt people with his sand; it's not as if the United States was not currently fighting a war, in a desert. Or as if families of active duty military did not get unlimited free health care. (Granted that he's currently a fugitive from justice, still, if the man can't convince the US government to trade one free pardon in return for a guy who can single-handedly kick the ass of the entire city of Fallujah without getting scratched, he's just not trying.) Hell, even if he just supplied sand to the construction industry he'd probably be doing better than robbing banks.
Eddie Brock "praying" to God to kill Peter Parker for exposing him as a fraud comes off being more funny than creepy due to Grace's whining delivery. Possibly intentional, since Brock being a pathetic whiner unable to take responsibility for his own actions is sort of the point.
It's also difficult to take Harry's "evil plan" in the middle of the movie very seriously due to things like the end result of hurting Peter like this not being very clear, the fact that MJ could have put a stop to it if she just told Peter that Harry got his memory back, Harry's line of revenge (or the pie) tasting "so good!" and the strange face he makes at Peter from the window. What even was that?
Peter's dance number has become legendary in its sheer narm, especially because of the Mood Whiplash afterwards.
Emo Peter has become one of the sole things people think about in regards to this movie. He's either a case of Never Live It Down or Ensemble Darkhorse depending on who's talking about him.
One-Scene Wonder: Before the film's release, Stan Lee considered his cameo in the movie to be his personal favorite up to that point.
This also applies to Venom, who appears in the movie for ten to fifteen minutes but does a lot in such a short timeframe, not to mention that he gives a memorable battle against Spider-Man.
In fact, this was originally the plan, for the movie to be released in two parts with the second one being very Venom-focused, but the studio didn't allow it. It's Harsher in Hindsight now, since Hollywood is constantly releasing two-part movies these days.
Also Bryce Dallas Howard as Gwen Stacy, who could have left more of an impression and had more of a relationship with Peter and MJ had it not been for all the other characters and their arcs fighting for screentime.
Not to mention Sandman, who had many of his character arc scenes deleted and his original, much more conclusive send-off changed to one that doesn't answer any questions as to what he's going to do now.
Tough Act to Follow: Spider-Man 3 had the unpleasant task of following up on the near-universally loved Spider-Man 2.
What The Hell, Casting Agency?: General consensus is that Topher Grace was the last person one would cast for Venom. Word of God says that Topher was cast because Raimi enjoyed his acting and thought he'd make a perfect Anti-Peter Parker. Basically, the casting was more about this version of Eddie Brock than it was about Venom - which didn't work out for them in terms of fan reaction, as most fans either don't really care about the Eddie Brock part of Venom, or think that the usual version of Eddie Brock is much more interesting, at least after his Character Development and in the animated adaptations.