Does your opinion of a character, like Littlefoot, differ among the films? It sort of does for me. I considered him a brave leader in quite a few, but a bit of a stupid kid in 6. I saw his as being quite decietful in 11, also.
Then there's Spike, who is usually quite the same. There is a few differences, though. Movie 5 showed him sort of as a bit of a loveable jerk---he showed off that he could cross the log with his eyes closed after Cera was scared to do it, breathed in Ducky's face after eating stinky flowers, ate Littlefoot's last treestar without considering if he wanted it, and so on. Movie 6 portrayed him as more of the woobie. You feel sorry for him nearly the whole time. First he's scared to death to cross the gorge, then he nearly gets ka-bobbed by the piece of Saurus rock, then he gets his tail stuck in a log with a sharptooth behind him, and just when you think he can't suffer anymore he gets his tail stung by wasps...ouch.

But, we see him all smiles and having a great time during the song "Bad Luck", so the movie doesn't end without him getting his icing on the cake!
Movie 8 went deep into Ducky's restrained darker side, and movie 6 stripped her character down to the bare essentials, but movie 7 portrayed her at perhaps her most loveable ever. (Yes, even above movie 1, perhpaps.)
Cera spends much of her time in 1 being a b**ch, wheras in the next 3 films she's quite soft and loveable. 5-8 portray her as slightly angrier, as fans have pointed out, and she is quite a b**ch in 9. 11 and 12 move into her more sensitive side, and the viewer might feel sorry for her, particularly in 12.
Petrie portrayed notably sillier, I think, as the sequels go along. Movie 7 gave us a really whiny Petrie---more then usual.
But this is all just me. What about you?