I re-watched Rain Main a couple of years ago, and I must say that it aged extremely well. I loved every minute of it, and I listened to Hans Zimmer’s score afterward for like 2 weeks. I’ve never heard that people hated the score and soundtrack, which sounds harsh and unreasonable to me, and I don’t get it at all.
Indeed I agree that this is Cruise’s film for 100%. He changes, as you mentioned, and evolves into a human being from an insufferable prick. His transformation is dramatic, emotional, and touchy. Easily relatable, and he nails it without any hesitation.
Yes, only the ending lacks perfection, and it doesn’t feel satisfying enough, even though, we now know that Charlie Babbitt became a rather good person who learned to understand the people around him and express his suppressed emotions.
“Rain Man” is a classic, and it deserved every one of its Oscars.