I've worked with Andalusians for a time. They aren't my cup of tea because of the "sparkle", I guess. A lot of people flock towards them because of their beauty and while that's perfectly fine, I like the rejects better.
Anyways, the breed seemed very well tempered as a whole, smart, athletic and agile. You can obtain false collection very easily so if you're into dressage, please know and understand the difference between actual, true collection and false collection.
The stallions I've worked with were good tempered. The mares were sweet. The foals were...well, foals! Their motion is fluid and sweeps the ground. The ones I've ridden had bucks like a rocking horse and were very easy to sit and drive through. They can be quick and sharp when they want to be bad.
Depending on the discipline, saddle fit might be difficult. I knew a woman who had to buy her Andy stallion a custom western saddle because every other western saddle didn't fit him. I've never had much of a problem fitting dressage saddles though.
You have to take care of that mane and tail though. That's quite a hassle in itself. Cowboy Magic will be your new best friend.