I've seen him play number of times for the Chelsea youth team, not to mention seeing him rip up the Manchester United youth defence.. I also watched a load of games from the recently played U19 Euro Championship, where he was very impressive. Jack Wilshere seemed average for Bolton, and isn't really a youth as he is nearly 22, where Kakuta is still a teenager and is playing at one of the best teams in the world. I'm sure if Kakuta was given a loan like Wilshere, he'd impress just as much, if not more.
I think Kakuta is one of mainy good Chelsea youths though, such as Matic, Delac, Jack Cork and Patrick van Aanholt, who has been out on loan and was impressive playing for Newcastle, especially with his long range efforts..
But I've said before that the Arsenal youth team is better, just the focus around the youth teams is much different, and not for the better.