Ambitions works just fine for everyone who knows how to evaluate the required hardware specifications and manage the cc in their game. You will find guides to both in the Help section:
Game Help:TS3 System Requirementswiki - don't install the game on an underpowered machine.
Game Help:TS3 Patching:Before You Beginwiki - before you install a new EP or patch, follow this guide. Check all your hacks for updates. If a mod hasn't been confirmed to work with the new EP, don't put it back in your game unless you are testing it in a throwaway game.