The only thing that might be unsettling when one thinks about it is the seeming change in the series that began with movie XI. Prior to that, the movies starting from II had a basic formula, albeit one that could be approached in many, many ways; something happens, the five characters meet a guest character, there's an adventure, the adventure ends, the guest character has to leave "if we hold on together" plays, and everyone says goodbye (except in the land before time III, where Hyp, Nod and Mutt just stay inactive.) No guest character becomes permanent, and, with the exception of Chomper (and his parents), no guest character is (yet) seen again (save for some possible cameos.)
Then, in movie XI, that changed. Tria became a permanent character. In movie XII, Tricia became a permanent character. In the first episode of the series (which I haven't seen, but have read about), Chomper and Ruby become permanent characters, as do Redclaw and Screech (probably.) So now we have a larger group, permanently changed for the first time. We also have the series' first regular villians/antagonists in Redclaw, Screech, and that other of the two raptors he has with him. Ironically, the series has become dynamic by keeping characters from leaving at the end, which is what we are used to. We might also see the return of other past characters, but no specific evidence of a return is given. I'll check various online credits of the series and see if I can't find a reference to someone who has yet to return...
The good news is, that the original group of five is still intact within the group of seven, and we aren't going to see a rotating roster like every new season of the "power rangers." If anything, what we are seeing is a natural part of life, which doesn't remain static; it changes.
EDIT: We have also seen the characters themselves change, and they have done much to overcome their flaws, they have gained/met family members, and all have grown physically:
1. Littlefoot has become more emotionally mature; we see that he is able to separate himself from his father in the tenth movie, wheras in the first movie, he probably would have (literally) clung to him. Of all the characters, he has probably done the most to overcome his flaws (attatchment, maybe even fear of loss.)
2. Cera has gained a stepmother, half-sister, and has become more tolerant of those of another kind. The same could be said of her father, who has also become more tolerant, though still thinking his kind is supreme (see the fifth tv episode.) Cera has also done much to overcome her initial character flaws (hubris, intolerance), but still has much pride.
3. Ducky is probably the only character who hasn't shown much change, although she is probably less gullible than in the first movie (not much less.) Her other flaw of sensitivity is still there, but this is also a part of her kindness, which is a positive quality.
4. Spike can now talk, even though he doesn't do so often, and hasn't really changed much otherwise. Spike hasn't done a thing about his flaw, gluttony.
5. Petrie has changed for the better and worse; on one hand, he is able to fly, since WAY back in the first movie. He also appears to be both braver and still somewhat easily frightened, depending on the cirumstance. He has also gained the fear of bad luck, probably from his experiences in the sixth movie and from what his uncle Pterano told him. Petrie also undergoes some sort of change in the twelth movie, but it probably isn't a coming of age ceremony, as he and his siblings are way too young.
Some flaws yet to overcome include superstition and unwarrented fear.
6. Chomper changed in when he gained the ability to talk somewhere between the second and fifth movies. We also know that Ruby and Chomper seem to share some sort of mutual responsibility to protect and guide each other, with Chomper having to lead Ruby to the Great Valley, and Ruby having to discover the secret of how to live together in peace with other species. It's hard to find much flaw with Chomper, but it's possible that he also has some gluttony; when he suggested bringing Tria some insects, Ruby said that he would eat them all, in the same manner that spike would eat all of the leaves that they could bring to Tria. There was also the scene in which he said he was getting hungry... with potential food trapped on a rock with him... and Ducky getting worried about this...
7. Ruby is the hardest to talk about. She appears to be the oldest of the entire group; she is larger than Chomper despite the fact that her species was nowhere near the size of Chomper's when fully grown. Anyway, what little we yet know of her deeper character comes from the third episode. She seems to suffer from some form of separation anxiety from her family; the scene in the third episode ("remembering") is similar to the scene in the first movie where Littlefoot was depressed due to the death of his mother. We don't see much change in her, save that of physical growth; she looks much smaller in the flashbacks, especially the one that was at least two years ago. I can also say that Ruby's verbal characteristics are to use mistaken logic and redundencies such as "but you haven't seen what we're going to see yet" (redundant) or "when all you have to do is wait, waiting is easy to do." (not necessarily, especially you're surrounded by lava, as she was when she said that.) Besides the logical fallacies (REAL philosophers don't use logical fallacies), another flaw which we could see overcome would be the similar attatchment that we saw in the first movie with Littlefoot.
