His handle is fine, it just isn't elite. He also has no trouble getting his own shot, and he played against some ridiculous competition last year.
Some people will nitpick because they're fixated on getting a Big, whether or not the Big is as good a prospect as Porter (and most everyone I've read thinks that Porter is the best prospect for '18, sans Doncic). That's not to say I'd be disappointed with Ayton. He looks like the most talented big in the draft since Embiid, and one of the top 7 footers of the last decade. Others like Bamba, but I have my doubts about him.
IMO, Porter looks better at this point than any of the '17 draft class did at this point. We'll have a year of him at Missouri to see whether or not that holds true.
If indeed we wind up with a top 3 pick, or praise God, 2 top 4 picks, it will be interesting to see what Ainge does re: Doncic. And whether or not scouts feel he can play PG in the NBA. NBADraft.net has us with the 1st and 3rd picks, taking Porter and Ayton. We'd be stacked beyond belief for years to come.