I think he's the big thing right now. I actually liked watching him play in college...but I watched the game last weekend and saw him laughing and joking on the sideline when they are down 25 points. I just don't see him having the maturity to succeed in the NFL. Plus, he has struggled every-time he has taken the field.
I honestly think his story will be similar to Ryan Leaf. He has the talent and the ability...but I think the lack of maturity will do him in in the long run.
The funny thing is, I was just getting out of the hobby for the first time when Ryan Leaf was a rookie. His stuff was HOT at the time...just like Manziel now. It was miles beyond my budget in 1998. I picked up one of his "big" 1998 cards just the other day for next to nothing...I got it because I could remember when it was so expensive and it made me laugh.