It's really hard to explain if you haven't watched him. You can tick off his qualities, which on paper are pretty much a full set for a striker like him: he's fast, has great balance and good strength; he's a lethal finisher, both in terms of being able to score all sorts of goals (long-range rockets, deft headers, flicks in the box, clinical ten-yarners etc) and having that knack of being composed and clinical when chances fall to him; he loves to make runs in behind and has excellent timing on the shoulder; he's also good with the ball, has scored a handful of stunning dribbling goals and throughout his youth career has always been involved in the build-up play alongside teammates like Januzaj, Pereira, Daehli etc; he's a hard-worker, and likes to defend from the front; his decision making is mature and reliable, which in combination with his pace is what makes him such a good counter-attacker; he's actually got good passing range, although obviously you don't really want him involved early enough in the move to have to show it. But see his near-assist for the England U21s vs the USA recently as an example of his eye for a defence-splitting pass.
He's also just got that x-factor, which you develop an eye for if you watch a lot of youth football. For me, the likes of Welbeck, Macheda et al never had it - they were special players in the reserves, and certainly had their moments as senior players (I'm still a massive Welbeck fan tbh), but I would never have put a load of money on either making it with us. For what it's worth, I think Pereira's a superb footballer but I don't see it in him either, he still doesn't seize matches despite his absurd technical ability. The only three PL youth players I've really seen it in since a young Wayne Rooney are Wilshere, Pogba and Januzaj.
But as you say, lots of fans of youth football claim to see 'that x-factor' in lots of young footballers, so it's hard to take someone else's word on that. What really sets Wilson particularly apart for me is the sheer relentlessness with which he has scored goals at every single level. Trust me, even the good strikers just don't do it that much in the English youth leagues. It's hard for either teams or players to be consistently prolific because of the stop-start, chop-and-change nature of the football, and because of the regrettably low-intensity matches that you sometimes (not always, but sometimes) see at those levels.
But from U16 level onwards, in terms of goalscoring Wilson has just looked like a senior player amongst kids. In periods where we've been the best around and thrashed plenty of opponents, he's had several 4- and 5- goal games. In periods where we haven't looked that handy, he's still popped up with a goal a game, and a handful of hatricks. He's particularly notable for scoring in the really big ones, and when it really matters. He scored all four goals against City in a crucial 4-0 win two seasons ago - a game where we weren't really even the better team, believe it or not - and then scored the key opening goal in the same fixture this season to effectively guarantee us the title.
Before we bought him the only full matches I'd seen from Martial were the Juve and Arsenal games. Since, I've obviously watched a daft amount of highlights footage. He's gifted, but in a load of videos which are designed to show his very best moments, I've seen nothing which I wouldn't not only feel Wilson to be capable of, but expect Wilson to produce as a matter of course.
And let's not act as if he's really been given opportunities with the first team yet. Giggs gave him game time and he scored a brace in his debut. Since then it's been a handful of sub appearances for a team that was all over the place last season, whilst Falcao got game after game after game despite showing no sign of being able to score goals.
In this team, with a very solid-looking defence, an embarrassment of midfield (both DM and AM) riches and an obvious strategic foundation to build on -a team that has every ingredient, really, except a fast, direct, running striker to score the goals - Wilson would score at the very least a goal every two games if he was playing regularly. More than that if he was first choice. You can scoff, but I'm the one who's actually watched him. This is a special, special young striker.
What a player he was, the best youth player i watched after Ravel. Pure class, shame about the injuries.....