pretty hate machine
I would image it would be harder to train an owl. Aren't they, typically, a lot smarter than say hawks or falcons? They're harder to train, but it's not because they're smarter...a lot of people who work with owls will reluctantly admit that, all told, they're kind of stupid. It's not that they're smart and figure out your tricks and are therefore resistant to training, it's that they seem to take
forever to get it through their heads that X means Y.
They're also just physically unsuited to human contact and training. Humans are offensive to them, we're loud (very loud) and quick and exist in bright light. They also don't have what's called a "crop", which hawks, falcons, and eagles do, where they'll eat a bit of food and it goes into a little pouch on the front of their neck before moving on to the stomach.
with owls, the food goes straight to their stomachs, so it's difficult to tell when they're getting 'full' and when it happens, it happens suddenly. So they'll go from being interested in you to suddenly full and not wanting to do anything but fly up into a tree and digest.
All in all it takes considerable patience and an experienced, careful falconer to correctly train an owl and keep it healthy. Most of what I know I learned from one of the king of Spain's royal falconers who works almost exclusively with owls, she talked mostly about how owls need to be shown something again and again and again very gently and quietly before they seem to get the idea, and they don't tend to pick things up on their own as quickly as a hawk or falcon.
but, once correctly trained, they can make amazing partners.