The Sixth Sense (1999)
Review
I liked Sixth Sense in general. I dunno about best of all time, but it was good. Haley Joel Osment's acting in particular is a clear standout. He's running circles around most of the other actors in the movie. The scene where Cole is seeing the hanged people in the school. But we the audience and Bruce Willis don't see them. And he's desperately trying not to look at them even though we can tell they're just on the edge of his vision. Great stuff.
I do have a problem with the ending. It's just so sudden. I strongly believe it was Shyamalan getting bored after doing his reveal so he decided he was done with the movie. Because it's all about the twist.
First change I would make is get rid of that bad line where Cole tells you everything. The "they're walking around living their life and they don't even know that they're dead" line. Where he is staring directly at Bruce Willis. The twist of the movie is clever, so let it be clever. The line is too obvious and reveals the whole thing way too early. So just get rid of it. Change it to where Cole reveals to Bruce Willis that he sees dead people and we move on.
Second, let's get to the ending. Bruce Willis realizes he is dead, then there's a bright light, and credits. It's way too quick and we're not properly resolving the relationship between Cole and Willis. I think a more appropriate end is Cole convinces his mom that he does see dead people after their scene together talking about her mother. Coles starts to worry that he hasn't seen Willis in a bit so he has his mom take him to Willis' house. There he discovers that Willis' realization that he is dead has made him mentally unstable. Similar to Willis' patient in the beginning. But Cole helps talk him through it and tells Willis that he helped Cole deal with the ghosts. This makes Willis realize he has done well despite being dead and he feels better. With that, you have a nice parallel to the beginning of the movie. Willis couldn't help his former patient in life. But he helped Cole after death, who in turn helps him.
Something where you get the two back together after the reveal and we can properly wrap up the relationship between them. Perhaps have a flash-forward of a few months where we see what's become of Cole. You could have a whole fun duo where Willis and Cole go around helping ghosts come to terms with their deaths. But as is, the movie just ends. I think expanding on the end would really help the structure, but Shyamalan didn't seem interested in that.