Smart was never ever designed to be a PG. He can guard both positions pretty well, his wingspan/bulk helps him make up for his height disadvantage on PG/SG.
His game reminds me of a less speedier Westbrook. He can get to the foul line, makes the occasional good passes, and can finish inside while having a decent mid range/ and inconsistent 3 pt shot. But he is a SG forced to play PG. And while there is nothing wrong with that as Smart is smart enough, (pun not intended,) to be able to switch to both regardless. I just think Smart is more effective at the 2, but once SL, I bet Brad Stevens will toy with both positions, and see which fits him best.
I would dare to say Smart has one of the best defenses I've seen in any of the rookies this year easily. Smart doesn't ever look lost on defense, and sometimes unfortunately has to try to team help more due to the lack of direction his teammates had at Oklahoma.