As a fan of Pixar, MI, and Randall, I definitely want to see this and I am quite jealous that you were able to see it earlier Pterano. :nod
My initial fear is that the film is going to put way too much empahasis on the frienemy relationship between Sully and Mike, making other characters more one dimensional, stereotypical background characters than anything else. I have no problem with characters being in more supporting roles, but at least still make them interesting.
With Randall, I'm worried that they will make him too unrealistically sweet that you could never see the gradual shift between who he was and who he turned out to be, or they just make him a slimy character through and through. AND I'm afraid that he's going to get a brush off, making him just a plot point character. And even if Pixar DOES a good job with with Randall's character arc, it's going to make me sob in the theater.
Oh god, don't even get me started on A Bug's Life or The Incredibles. Honestly, I think a prequel would be interesting for A Bugs Life, especially if they made it more like a slice of life kind of story. Because really, a sequel to A Bug's Life, I'm afraid it would borderline on lazy fan-ficcy material. I mean...they're going to make Finding Dory thanks to the popularity of her character.