If by overrated you mean that he is getting a bigger reaction than most babyfaces in the world, then no. However, and I may catch heat for this, I do believe that he is getting the support he's getting BECAUSE OF the treatment he's gotten from Miz and Cole. Remember the old addage: wrestling is about the bad guy being so bad that you want ANYONE to beat him, and if he is bad to someone, you want that guy to beat him that much more, despite how you felt about that guy previously. That is exactly what has happened in Daniel Bryan's career.
Go back and watch NXT season 1. Bryan got a decent reaction, but nothing spectacular (trust me, no one got huge reactions on that show). However, as the show went on, it was clear that WWE was investing time into the story that Bryan might not look great, but is. They milked the story with the perfect foil, The Miz. No one in WWE gets more heat than Miz, and to pair him with Bryan and have him belittle him on a weekly basis gave Bryan a basis for sympathetic cause. You must remember that 90 percent of the WWE audience has never seen a Ring of Honor show and don't care to. Thus, they don't care that Bryan "has til 5" and they wouldn't think it was cool if Bryan came out to "Final Countdown". They see this guy as truly starting his career now that he is in the WWE, and in some ways, he is. Certainly the financial aspect is a step up from Ring of Honor.
Keep this in mind though. While crowds in Japan might be large, performing on the Indys in America will never provide you with crowds more than a couple of thousand. He may have been over with those crowds, but they are regional and small. Bryan is now over with millions of WWE fans and that doesn't happen just because the smarky audience wants it to. It happened because Bryan's booking has been absolutely perfect, he had the perfect heel to work with, the berating by the announcer helped, and even getting fired made him a bigger star. All of it created this sympathetic figure that people want to see overcome the odds. When Miz says that he's "like you guys" to the audience, perhaps that actually helps him. Bryan is small and goofy looking, not a pretty face like Miz. Thus, people relate to a "real" guy. A real guy who trained under HBK, but a real guy.
I will say this. Coming into NXT, Bryan was overrated by the IWC. They touted him as a star before he started to become one. However, proper booking has gotten him to a good place. I don't know if he'll ever be a top champ so this might be the pinnacle (which might be depressing but it may be true), but he got there because of great booking by WWE and a great job by Miz and Cole of playing their roles to make Bryan what he is. Bryan did his part and wrestled well when called upon, cut a few decent promos, and got fired at just the right time, but he was given every opportunity to succeed and did. If he didn't, then he'd be a total failure.
With all that said, he still annoys me because of his smile and stupid faces he makes. He really needs acting lessons because it's quite annoying and I want to smack him. His smirk is heelish and dumb looking. Fix that minor problem and shave the beard so it's just a 5 oclock shadow and not out of control and you really have something.