Arsenal's young players tend to get overrated more than others, mostly because they are exposed to high level first team football at a young age, and develop faster than young players in other teams that maybe do not get as much chances, Wenger is very good with giving young players confidence too, the problem with this approach is that at a very young age they peak, and they just don't get any better.
Walcott is a prime example of this, i personally don't think he's getting any better than he already is. He's got amazing pace, but really his technique is lacking and on the ball he's not a very intelligent player.
Gibbs too for me, is not all that special, he will keep developing i think as he gets more chances, but he too is not the most intelligent player, and i doubt he'll be another Ashley Cole.
Ramsey is another overrated player, who is considered some big talent.
Even Chamberlain with all the aura around him, i don't find him to be a particularly intelligent player or a very skillful one either. He's built like a bull and he's got lightening pace, but i for one, am not completely convinced that he will develop into a world class player.
The only Arsenal youngster i'm actually convinced could become a really good player, is Jack Wilshere. Now that kid is special, i will never forget how he dominated Xavi - Iniesta in the second half of that game against Barca in the Emirates a couple of years back.