Chiggy is a very talented defender; smart, cool-headed and athletic. I think the main reason Guardiola rates him so highly is because Chiggy is a kind of CB who likes to be a leader, both in defense (like Puyol or Carra) and in the first phase of attack (like Pique or Marques). I have to say that this quality makes him quite infuriating to watch when he's off his game - on occasion I wanted to throw some heavy objects at the screen last season, but then I remembered to tell myself that I should respect a player who is not afraid to stick out even when things are not going right for him.
Anyway, Chygrinsky is a talented and very intelligent lad, not quite a finished article yet, but he has world-class potential. I will be following his progress at Barca very closely. I think at the moment he shouldn't be more than a 4th choice CB in the already stellar Barca defense, but who knows what Guardiola is thinking. Certainly a 22 million investment means he really believes in the player.