Pixar truly care and take their time on their projects unlike Disney who just fire them out one after the other to make as much money as possible. The quality of Pixar films are always fantastic and I think one example of Pixar sequels being surprisingly good is Monsters University.
Pixar have always been pressured by Disney to make a sequel. Pixar are the type of people to take their time with their work to make it the best work possible. When asked about it in interviews, Andrew Stanton always said that he'd rather make a great film than a quick one. By the time this movie comes out, it'll be the ten year anniversary of the first one.
They are not going to do a rush job of this and I think they're going to slow cook this to perfection. Elle Degenres did say that "if you loved the first one, you'll love this one."
You have to consider that Dory is always lost and even if found will never be found. As such the title is misleading in that Dory can never be found ever. I have a feeling that children are going to come running out of the theater in fear of Dory's lost mind. ;)