No better than MT2 (No worse either...)
Cheats and 1000 maps are no substitute for testing. I played MT2 all the way through and hoped that you learned from that one but MT3 is again full of bugs and balance issues. Other reviews have detailed them so I won't bother. I enjoyed what I have played of MT3 but it does not seem like a step forward.
As a side note it would be nice to know, at the beginning of a map, if the enemies respawn endlessly or if it is possible to kill them all off. Little is more frustrating than killing the last guy in your way just to have him respawn and knife your last unit.