Let us take a moment to send out some love and healing energy to the screenwriters, Christopher Markus and Stephen McFeely. 
They had to juggle about 67 Different characters, making sure that each one gets a moment, make sure there's a solid dramatic arc for a core group, keep the momentum going while delivering the big, bang, CGI moments at regular intervals.
In short, imagine Robert Altman's NASHVILLE with three times the characters and every twenty minutes, they had to fight a Mech-suited Henry Gibson.
That's the kind of shit that'll turn a word jocky's pubs white!
I don't know if they succeeded yet, (The film doesn't come out until April.) But damn it, you have got to admire the effort.
As for the trailer, it is what it is.  Which is mostly awesome! Thanos is set up as a credible threat. We see Star-Lord trying to convince Tony Stark of his awesomeness.  We see a lot more of Wakanda. (BTW. Finally saw BLACK PANTHER last night and man, do I have some stuff to say about that one. All of it good.) We see Peter Parker being adorably awkward around Dr. Strange.
We also see a good chunk of the big, bang, CGI moments in case you were worried about them shortchanging you there.

So yeah, I'm in the pipeline for this.  I've been following the Marvel Movies since 2008 and you bet your sweet bippy I'm going to be there to see if they stick the landing.
Also, those of you complaining that we may be losing Captain America.  Let me say this.
Chris Evans hasn't had any carbs since 2011. 
The man has sweated blood for this franchise! FOR THE LOVE OF GOD, LET THE MAN GO IN PEACE AND HAVE SOME GARLIC BREAD!!!