Very underwhelming. The Hulkbuster looks like a video game compared to Optimus Prime of 8 years ago. There is nothing innovative about the trailer except for how dull that they can make it.. the piano didn't help.
Anyway, effects wise, the Hulk keeps looking better and better, and I can't help but wonder what's stopping Marvel from making a solo Hulk movie. Fans want it, they have the right actor, the best effects..... Perhaps story is an issue? We can't do an origin story, unless we see it as a prequel of sorts. And are fans willing to see movie set before EVERYTHING we've had over the last 7 years. And, basicly, Edward Norton's Hulk is part of canon, with the inclusion of Tony Stark, and a gazilion little hints to so many parts of the MCU, including the SuperSoldier serum and SHIELD.
Right now, I'm mostly curious as to what part Quicksilver and Scarlety Witch will play.