I don't have a stallion, but I have worked with one quite a bit and would eventually like to be able to have a very nice stallion.
There is nothing quite like having a stallion, nothing compares to riding one IMO, but they're a double edged knife. If you don't assert yourself with them from day one and make sure they understand you're the boss they can be extremely dangerous. I can't tell you the horror stories I've heard.

I was at a show last June and there was a young 3 yr old stallion in the warm up ring.

First, let me say, he was rank. He should have been gelded asap, he wasn't stallion material and he was very aggressive.(Which is my pet peeve about some people and stallions, they have a colt and just don't have the heart to geld them and breed them for the prestige. A stallion needs to have excellent conformation, temperament, and gaits!).
Ok, rant over,lol.

He took him into the ring and didn't even get a whole lap of the make up arena before the stud started rearing, bucking,bawling, and farting. Needless to say he never actually made it into a class.