I'm not sure if they changed anything and I have not kept up to date,but they had some pretty bad reliability issues,especially with the drive train. The gears were very poor,got chewed up really easily and the whole gun liked to shake apart internally. They might have remedied the issues with newer ones,again,I have no idea.
Can;t guarantee they will give you an edge in combat but they should be an absolute blast to shoot since the recoil is pretty heavy.
honestly,the recoil is the main draw of it,performance wise they're just like 90% of stock AEGs. if you want a recoil rifle without reliability issues then the KWA and Marui ones are better bets,but more pricey. If you want a nice reliable rifle G&G are the way to go.