Lukaku isn't an absolutely elite striker, I'd say there are quite a few players ahead of him. Lewandowski, Kane, Cristiano, Suarez, Haaland, Benzema, Aguero, Aubameyang, Werner, probably even Ibrahimovic. He's in the same mould as guys like Immobile, Icardi, Cavani, Morata, Vardy, etc. for me.
However, if you had never seen anything from Lukaku, read this thread and then go on to watch one of his games, you'd be up for a huge surprise I guess. Judging by this forum, you'd expect an absolute anti footballer that muscles in a goal occasionally. Yet when I see him play, I always see stuff that really impresses me from a technical point of view. He's got great hold up play, can beat a player and also has some silky skills in his pocket, like a great cross with the outside of his foot etc.
He might be a prick, I don't know (as far as I know the quote about him saying his positioning can't be wrong was ripped out of context), but the toxicity towards him sure feels a bit over the top.