I have a feeling that they are being very careful about what and how much they show of the film. And so, there might actually be loads of stuff we havn't ssen yet which will make the movie even better. I saw the same thing happen with Spiderman 3: i saw all the clips and trailers and got this first idea of what i thought the atmosphere and tone would be like, but when i saw the fil i was stil surprised by what happened because some of the things i had never even heard was gonna happen - for instance the bit where Peter Parker starts dancing in the street; i would never have seen that coming.
I think that most of the clips we're still seeing, over and over again, are good enough as long as this sort of limit is whats gonna keep the movie experience as surprising and as uplifting as ever expected. This is exactly what i enjoy most about films and it is what, i feel, makes them good movies.

And YES, i would also like to know what the whole Lupin materialising in the air is all about. I mean the only reason for it is them appearing dramatically (and fluently) at the Department of Mysteries scene. To be honest when i see that Lupin materialising bit it reminds me alot about the fourth movie when harry's parents/cedric/Frank Bryce appear spiritually from Voldemort's wand. On the other hand, i have to admit i cant wait to see that bit where Lupin materializes like that.