For one... a 94 yard drive that had numerous good runs and passes in it. Felix was thisclose to breaking a 94 yard TD run.
Another thing is on a different drive, they marched down the field smartly, with Ogletree catching a couple of passes that was perfect execution on his part. That drive should have ended up in a TD, but when Romo went deep for Ogletree, a defender got in his face and kept Tony from stepping up into the throw and so it was intercepted. With better protection, that probably was six points. On that drive, the offense looked good. Good protection for the most part and good run blocking.
So on those two back to back drives (INT drive first and then TD drive), it was easy to see how polished the offense is, how sharp Tony has been, how good the passing game will be and how good the running game will be. In short... they looked good.
Also, the first string defense did pretty well in keeping San Fran from moving the ball. They went 3 and out for a couple/three series in a row, and they were doing pretty good with pressuring the QB. Overall... the defense looked good.
So, when the offense and defense look good... you can come away from a preseason game feeling pretty good about where the team is. Also, the special teams started gelling last night.