First thing I noticed after watching:
No mention of Lost Lords, or swords, for that matter.
Caspian and Eustace are getting much less screentime in the trailer than expected. (A bit more eustace wouldn't have hurt)
Other observations:
Edmund wants to enlist in the army?
Why? Did Ed find so much liking in wars that he wants to enlist in wars on Earth as well :? ?
And then the line "I'm a king". Reminds me of PC Peter.
The Picture: I always pictured the picture (pun intended) with the Dawn Treader more in the foreground. It's mostly water.
Eustace ripping off the Picture is perfect

the transition was made more "cinematic", and in a good way. That's one change I actually like.
Dawn Treader: Nothing new, besides the Sail which looks much different, and much better, in my opinion. Some sort of Emblem on it
Minotaur: looks very CGI-ish, very unlike PC and LWW?
Mermaid: Not much to say, Lucy waves to her, but it seems not to be the Merpeople from later on.
Reepicheep's voice: Doesn't sound much different from the old one honestly.
Dark Island: Honestly looks more like "foggy Island", if you ask me. From the outside, AND the inside. And then: WHY is there green stuff flying around in the island? The Dark Island is not really "dark" anymore. Don't like.
Jadis with GREEN eyes, surrounded by GREEN fog: I wonder if that is supposed to mean that the dark island is actually the Lady of the Green Kirtle's doing?
Magician's Book: Looks great, transition from Lucy to Susan is very subtle, but noticable (before the cut where Lucy touches her face which is mirrored by the book)
Rhindon glowing: They are apparently in the darkness of the dark island. Dark, but not dark enough, if you ask me. And then the fog is GREEN again. RHINDON is glowing BLUE. Does that mean instead of Aslan, we will have Ramandu's Daughter guiding the DT out of the darkness? And then, I don't know what the significance of Rhindon is supposed to be here.
"Extraordinary Destiny, something great than you could have imagined": Makes sense for Reepicheep, with his longing to the utter east.
Ramandu's Daughter: Now that was a little bit too much, if you ask me. The glow, her being as pale as it gets. If she only got an ice crown she could be Tilda in LWW
"The Fate of Narnia depends on you". Ugh. I hope this is something just said in the trailer. The footage of Ramandu's Daughter going Star Mode is sped up, as being visible by Lucy taking that step back. Honestly, I don't like that whole "Becoming star and human whenever I want" thing. Ramandu was a retired star. We don't know exactly about his Daughter, but the fact that they'd just transform at will in that way seems very much unlike the book.
Battle: Kind of Ironic how right after "Return to hope" they show an added battle. Behind the Faun is apparently Gumpas, as headgear and garb seems to match. He probably shows resistance against the abolishing slavery and re-instating someone else in his place. Of course they want to show of Narnian creatures, maybe that's why they added them to the crew?
Lucy apparently is training her archery (as per HHB). Ed has Rhindon, Lucy apparently has Susan's Quiver.
Dufflepuds: Very... jumpy.
Coriakin apparently is in the same room when Lucy says the spell-
Sea Lilies: Look great

End of the world: The water wall seems to be in motion, but the water really goes nowhere. Very weird effect.
"You have returned for a reason": Yeah, we heard that in some PC trailers as well

Pevensies in Narnian garbs: So, what are Peter and Susan doing in Narnian garbs? The footage of Lucy and Ed have the same background and Lucy having still the same outfit, indicating that they're still in Narnia. Apparently not a flashback, as Lucy has her regular outfit :? What's that supposed to be? And then, Peter looks different.
Aslan: In all the shots we see of him, looks much different than both previous iterations. All in all seems to have a darker mane? Kind of looks less majestic. Seems to be an entire new model again, modeled after an altogether different kind of lion this time. IMHO a step down from PC

Logo: Dragon scales apparently.
Also, what's with the snow? First in Coriakin's house, then with the lines ("From C.S. Lewis' Epic Masterpiece" <- wasn't this the same they said with PC? ) and then when the Dufflepuds are jumping around there is _something_ in the air as well.