Anyone been watching the USA U17 games on ESPNU? If you search "U17" on your TV guide, you can record the next three (Thu, Fri, Sat). I DVRed the Japan one on Monday, watching now. While it is only one game, it is a competitive, tightly-contested game (currently 110-31), so I feel that it is sufficient for conclusive player evaluations.
Everything about Tatum is just gorgeous. If Semi's body is the basketball equivalent of the girl with huge boobs, he's the swimsuit model. Legit 6'8-6'9, long arms, wide shoulder, built really solidly despite being so long. Reminds me of how Dwight Howard was built as a high schooler. He's not quick-twitch explosive, but he's crazy skilled, smooth, and long (er...). He almost has some 6'9-poor-man's-Steph-Curry in him.
Giles is very tall, long, quick, and explosive with a good frame. The potential SF talk is nonsense, though. Didn't look all that skilled, but doesn't need to be, obviously.
Ellenson is a slightly richer man's Wear twin. Dislike. Hope he goes to Wisconsin, where he could probably be pretty good.
Stone looked like a pretty safe bet to be a solid NBA center. He's not Shaq, but he's a baller.
Rabb was garbage and showed nothing. Maybe he just didn't GAF, but I would have guessed he was maybe 20-30 in his class, not top 3.
Swanigan, I don't know. Hard to tell much about a sneaky fat guy against a bunch of tiny asian kids.