Well, I'm biased as a huge fan of Marvel since I was a kid, but I thought the trailer looked great. This is the culmination of all those other movies further bringing the storylines and characters together, so if you liked the earlier stuff then this shouldn't be a departure from that. What didn't you like about it?
Thanos is a cosmic level threat in the comics, so it should take an army of superheroes to beat him and his goons (which were mostly not shown in the trailer). They've shown the heroes are vulnerable (Iron Man gets beat down, Thor loses his eye and hammer, Vision's losing his mind stone, etc.). I love the little details too like Peter's Spidey Sense causing his arm hair to rise. The big ground battle with Thanos's army looks like some good eye candy and the Guardians even pop in with Mantis waving hello. Looks like more of the same Marvel action/comedy magic to me.