I admittedly know nothing about the kid...never heard of him until this post and have never seen him play that I can remember. That being said:
His size is basically similar to Mike Gesell. 6'1" 185 pounds roughly.
As far as stats, Gesell has a 3.7:1.9 assist to turnover ratio and Sina has a 2.3:1.4. So Gesell turns it over a little more (.5 per game) but makes up for it with almost 1.5 more assists per game. Sina also averaged 7 more minutes per game than Gesell.
Sina shoots a TON of 3's. In fact, Sina would be leading Iowa in 3 point attempts right now. Sina shot more 3's already this year (125) than Gesell has in any full season. 125 3's this year is also 45 more than Jok has attempted this year and 11 more than Uthoff. Percentage wise, Sina shot 38% from 3 last year and 32% this year. Obviously 32% is not a good number considering how many 3's he is launching.
I think the most alarming thing to me is that he has 125 3-point attempts on the year and only 158 total shots on the year. That means he only took 33 non-3 point shots the entire season. To put that in perspective, Gesell has taken 131 shots from inside 3-point range, Uthoff 162, Jok 100. So this kid seems like he just sits back and launches 3's all day and does little else as far as scoring offensively
Again I've never seen him play so I don't know his game at all but those are the stats that stood out to me. He doesn't seem like a true point guard in the sense of how Iowa runs their offense. It also has to be taken into consideration the differences in conferences. The Big East is a good conference and are projected to have 6 NCAA qualifiers. Seton Hall's SoS is currently 35 so its not like they have played a bunch of chumps