I think the only major issue is that he tends to press and make impulse throws. I've seen good NFL QB's that press harder than Romo does, but it's still too much. Plus, when Romo misses it's usually high which tends to lead to INT's.
But people forget that the rest of the offense has been abysmal for the most part in the last 5 starts. We had FOURTEEN dropped passes in the Giants through the Eagles game, roughly 4 drops per game. In the Giants game alone, they had 5 drops with one of them bouncing off of Glenn's chest and into Kiwanuka's hands.
The running game has been very weak and the pass protection in all of the games sans the Falcons game, has been poor. Not to mention how badly the defense has fallen apart.
Football is a pretty simple game to follow. If you're running the ball poorly and not playing good on defense, your QB is put behind the 8 ball and is likely to struggle a bit. Combine that with poor pass protection, the QB is now more likely to play poorly.
The beauty of the "bus driver" mentality at QB is that it essentially means that you have built a good team and your QB isn't losing games for you because they are managing the game well. But right now we are not at that point. Too many parts of the team are playing poorly and we're not giving Romo good chances to succeed or even just be able to manage the game. Instead, he's got to make to a lot of plays to keep us in the game. While I think Tom Brady is a great QB and better than Romo, I highly doubt he would've done much better than Romo today if he had our O-Line, running game and defense to work with.
YAKUZA