Hard to gauge abstract things like "how good they are" and "how good people think they are"
By the stats, they are a very good team.
By their record, they are the best team.
By the "eye" test, I personally feel they are one of the most complete teams in the NFL.
I don't think they are overrated. They are beatable, and I would be shocked if they went undefeated, but they deserve their 4-0 record and have had some solid performances.