Prepare to unleash the absolute latest in modern weapons technology against the world's most powerful Generals in Command & Conquer Generals: Zero Hour. In the next era of military strategy and might, you'll need to command a more technologically advanced arsenal to defeat new, more powerful enemies.
It's an alright game,I invested many hours on it,but mostly only on lan-parties.
The problem with the game,just like with Battle for Middle Earth is that EA games made it ;P seriously thought,it's as if they didn't even try..there is no real difference between Easy AI and Hard AI except that it's scripted that Hard AI gets more money at the start and it's buildings and units cost less and take less time to produce,and that's literally all. It uses the same tactics as easy would,it can just master more armies,so it can spam them at your base while you gather your ranks and destroy their command center. This is the point where you won the game,because no matter how much money the AI has it won't re-build it's command center,which means that they won't be able to build almost anything,so once you destroy their last few builders,you are done.
Other then that I would like to point out the obvious OP-ness of USA,but this game has been out for so long,everyone knows that. I'm not saying you can't defeat them but they have some units and abilities which are simply superior to anything the GLA or China can offer.
All in all,this game can provide you with many hours of fun if you are ready for some compromises around balance.