Impossible to predict how Byram will be as an NHL'er because he's so young. I've seen him play a couple of times. He's not a highlight-reel type in the Hughes/Makar mold, as in you don't necessarily notice him throughout the game. But, he seems to be on the ice constantly, like dominant juniors tend to be, and by the end of the game he somehow has a couple of points. He makes smart, economical decisions - outlets, good reads, but not a lot of coast-to-coast plays, although he knows when to, and is very capable of, taking the puck the length of the ice.
But he is also needs to mature and given that he's only 17 (and a June birthday which makes him one of the youngest of the draft eligibles) that's hardly a surprise. He makes mistakes and takes stupid penalties that contribute to his high PIMs, and costs his team goals, but then comes back and creates goals or scores himself to make up for it. Not a bold statement, but I think he really needs his next two years of junior to develop and mature, which is why it's hard to say how he'll end up as an NHL'er. I don't think he's elite, but if I had to guess at this early juncture I would say second pairing with decent PP production - not a 25-minute, all-situations type.
If I was doing a fantasy draft I wouldn't take him over the top 10 or so forwards, if only because he's several years away from significant NHL production.