He's really nothing like Brady...Totally different player.
He has a much "bigger" arm (not necessarily better deep thrower, just bigger), and he plays into that by making big throws down the field. Brady it much more cerebral and accurate and plays closer to the line of scrimmage.
When the pocket breaks down, Rodgers uses his legs to get outside and keep the play alive. He can then throw or run for the first. Brady manipulates the pocket to keep plays alive. If its not there, he will hit a man if there is one open or throw it away.
Brady is much better in close games, much better composure. Rodgers seems to only be able to play well when they are winning. He has also shown less of an ability to come back from big hits.
Lets not even talk about decision making... Rodgers still makes some terrible throws.
You are right he has great potential, but he is still miles away from Brady and Manning. Keep in mind he spent a lot of time on the bench, so he is closer to his peak than other 3rd year starters. So far, he has not shown that he has the mental game (eventual his physical game will deteriorate) to stay great as long as manning and brady have