Don't get me wrong, PokeChen was one of the best junglers of his time because of the way you could constantly get the Centaurs (with the 2 second stun, and attack speed aura), Trolls (with the 1.5 second ranged net) and maybe a Satyr to round it out (for the life regen aura), grab 5 creeps and then Roshan before most people are even thinking about it. Then push all of the outer towers as the enemy team is either helpless to stop you, fodder for your 1500-2000 health creeps, or is porting in reinforcements causing them to lose experience
But as was said above, it requires a lot of coordination to pull off successfully. I rarely even see Chen played much, though I used to be extremely good at microing him and his minions. He falls off extremely hard late game, though, with no stun aside from what his minions can provide.
The creep stacking is one of the mechanics I've loved and hated, as if you do it well (especially as a carry, if you get Helm of the Dominator and stack the ancients with your dominated creep while you farm a lane, then go rape the triple stack) you become much harder to stop due to an increased gold flow, but if you are off by a second or get the wrong type of random creeps, you can be shit out of luck. Some Chen runs left me with no Centaurs, meaning no stuns, meaning a much harder time of ganking.