I think the biggest thing I saw from Manziel is that every time he got another drive under his belt, he was getting better. His first series was bad, although it had little to do with him. He made the correct read on the option, it's just Dray missed a block.
On his second series, he started out hot, then drops started to haunt him...was that the Dion Lewis fumble?
On his third, he found a little bit more and he was starting to hit the slant with ease again. It's easily his best throwing route, fitting into tight windows in perfect spots.
It's encouraging to see Johnny stay in the pocket and really sling the ball. We know what he can do on the move. His arm looks certainly strong enough, and his ability to move won't be hindered in the NFL. He's still making linemen miss and moving chains with his feet.
I really want to see Johnny with the first team offensive line. His progressions are slow and under developed it seems, although I think most of that was Manziel knowing that he only had time to get one read in before the offensive line deteriorated in front of him.
I was nervous that Johnny would come out, try to run around and buy time trying to do too much. If anything, he really does have the ability to control his emotions on the field and become a leader. He knew what he was doing at all times, he took control of the huddle. I'm not going to give him credit to recognize being a man short, although I'm sure it looks like an amazing ability when compared to dumbass Weeden.
For a 1st preseason game, Johnny did about everything you want. Obviously would have loved to see them get in the endzone, but with that offensive line and WR'ers, and not to mention fumbles, it was going nowhere. I'm feeling more and more confident that Johnny is the most talented QB on the roster, which means he's at least a NFL starter, IMO.
Edit: I will add that I think we did see some stuff that really does make Johnny special.
For example, the 4th and 1 play. Manziel took the ball and decided to run it. Obviously, the FB looked wide open, although it does appear early in the play that the route was primed to be jumped, either for an INT, pass break up, or the FB getting lit up. Instead, Johnny decided to run, make a man miss, and managed to make it to the first down marker. There was a point in the play where it would have been smart to throw the ball, but Manziel clearly has more faith in his legs. It's going to happen early in his career. He went out of bounds so I cannot fault him nor deride him for taking a shot. He just has to be smart when he runs.
The other...man, I have never seen a player who is so comfortable rolling to his left and throwing the ball. Manziel does it with such ease and accuracy, it makes him absolutely deadly on bootlegs. If the Browns get the running game going, and Tate is gashing holes, that offense is going to be very hard to stop with Manziel running bootlegs. We've seen Manziel's ability to make a guy miss, so if he gets into open space like that, and has options, he really puts the defense to heel. In game, Manziel did this to perfection, although...Sneed blows and he couldn't stay in bounds. If that's Austin, or Gordon, or Hawkins, or Cameron, that's a first down and you keep the chains moving.