The reason why he is so popular, because he created something that united the Mecca tribes. He wasn't just a general, but then again.. Christians did the same thing as the Muslims did. It was how it was back in the days, you know?
He was/is famous because he was the last line of Islamic prophets. Adam being the first and him being the last. He was famous because of his ways, he was a diplomat, a leader, a general, a shepard, etc. But pretty much he is famous for creating Islam, Islam united the people of the Middle East. Before Islam was created, there wasn't countries or anything.. it was just tribes and when created Islam, it removed the tribes.
They don't view him as the greatest, they view him as very honorable and with high respect because he was the last known prophet to exist. I'm not the one defending Islam or Mohammed. But, I figured I would clear things up before some moron does, you know?