He went there to kill Mal'Ganis. He was obsessed with saving his own people. To achieve that he did some questionable things, but he was not evil. He lost his soul to Frostmourne when he picked it up. It was a cursed blade. And even that he only did because he wanted to save his own people. That's why his story is so tragical.
---------- Post added 2013-02-26 at 10:02 PM ----------
Which is really not a point in the orcs' favor.
---------- Post added 2013-02-26 at 10:07 PM ----------
No, you still don't understand Garrosh's plan. He intended to drop the bomb on the city from the beginning. If it was all about just taking the city, he would not have waited so long. That was the plan. To wait and let the Alliance gather their forces. Because he knew he was just gonna drop the bomb anyway. It didn't matter if they faced 100 or 1000 soldiers. He wanted to get rid of a larger number of people and of a lot of high-ranking Alliance personalities.
People have pointed to several pieces of evidence that clearly show that's the case.

MMO-Champion
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