I just recently ranked Ellis at number 2 for my early season top 30 OHL draft eligibles.
I'm a big fan, of both him as a junior player and as a NHL prospect.
I'll try to answer some of your questions based on my viewings of him...
Yes, I think he is. His offensive ability is just outstanding for a defenseman, nevermind a draft eligible 17 year old. The hockey sense is tremendous in this area and I do expect him to keep up this pace and be the first OHL defenseman to hit 100 points since Jamie Rivers back in the day with the Wolves.
What's his style of play like?
His style of play is at this point considerably offensive, if you hadn't guessed by the point totals. He's a good skater who can lead the rush and the breakout. He's one of the best powerplay quarterbacks I've seen at this level. He controls the point with such composure and has one hell of a cannon of a shot, that's also very accurate and generates scoring chances off rebounds. He's also an aggressive physical player who will go for big hits and be physical in the corners. I think he could stand to be more physical in front of the net, just because he's so physical in the open ice. Defensively, he does have shortcomings. He can get caught on bad pinches, he can be taken out of position going for the big hit. But I think a lot of his defensive inefficiencies have to do with timing and experience. As he gets older, he's going to learn and improve defensively, I think.
How does he compare to Doughty and Pietrangeo?
He doesn't really compare to these two guys, different kind of players. Both of these guys are considerably better defensively than Ellis. They are also better skaters and a lot of their offensive game is created off the rush, rather than from the point in set up situations. However neither player knows how to use their shot as well as Ellis does and can run the powerplay as well as Ellis. Also, neither player is as physical as Ellis is.