World class is one of those funny terms that people understand differently.
He's an awesome player, no doubt, and if he continues like this he's going to be one of the best players in the world - no question about that. His new, drifting style of play is fairly similar to what Ronaldo does and it's working for him.
I personally take world class to mean that someone has the ability to play in pretty much any team in the world - and Bale does. On current and possible future form he'd be stronger for Barcelona than Pedro/Alexis Sanchez... Real Madrid, maybe - it depends how much you rate Di Maria, etc.