What gives me a lot of faith for Ant-Man are the following...
A) The story and characters - I love that it's a passing-of-the-torch type of film that is mixed in with a heist plot. Plus, I like that there is a focus on parenting (ie Scott Lang and Cassie Lang / Hank Pym and Hope Van Dyne). I know a lot of people are bummed that Ant-Man will not focus on Hank Pym in the costume. That said, I like that it's the Scott Lang Ant-Man because we haven't seen a lead character like him (a thief who is trying to build a better life for himself and his child) in the MCU before. And I think it's fantastic that it's an older Hank Pym because the character will have a lot history in the MCU. That just adds to the awesomeness of the MCU.
B) Casting - Paul Rudd, Michael Douglas, Corey Stoll, Evangeline Lilly, Martin Donovan, John Slattery, Hayley Atwell, Judy Greer, Michael Pena and Bobby Cannavale. That is one of the finest casts put together for a Marvel movie and no one can deny that!
C) Peyton Reed and Adam McKay - While Edgar Wright would have delivered something unique and different, there is no reason Peyton Reed can't deliver a great film. A lot of people just think Reed is a boring director with no vision. Untrue. First, if you watch his previous films, regardless if you liked the content or not, Reed knows how to make a good looking film with a lot of high energy from beginning to end. If Ant-Man needs anything, it's a lot of energy. Second, Marvel has been eyeing Reed for a while. He was the original pick for Fantastic Four years ago and he was the runner-up choice for Guardians of the Galaxy. Marvel Studios trusts him. So can we. He wasn't hired to make Edgar Wright's Ant-Man. He was hired to make Peyton Reed's Ant-Man based on Edgar Wright's story. Third, he is a MASSIVE Ant-Man fan! This guy knows the history of this character just as well as Edgar Wright. There is no reason to think Reed doesn't want to make the best Ant-Man film possible. Seeing that he has been working with an incredible crew, as long as the script is great, Peyton Reed's Ant-Man will be a homerun! Speaking of the script, I think Adam McKay's work on the script will only help the film in the long run. McKay is also a BIG fan of Marvel comic books and he took the writing assignment because he saw he could add some good stuff to the material. If Marvel Studios liked what McKay did with the Ant-Man script, I'm willing to bet he'll be directing a MCU (I'm thinking Inhumans) at some point soon.