They are, I loved letting mine out in the Spring after a winter inside - although I used to take mine out occasionally, he was never let loose. but in Spring he would canter out, and just run, hooves pounding, kicking up behind. Then roll and roll with legs in the air. He would usually take a week to calm down. Then there's the wind - he definitely got the wind up his tail! That would get him all excited too, more careering and spooking at nothing and balletic sideways leaps. I do miss him.
Expensive - well, we already had land and a stable block. He was supposed to help keep the grass down, but sweet itch and laminitis put a stop to that. Most of my friends were farmers, so hay and straw didn't cost much - I would help out with a sock lamb or three in exchange for all that. I bought my own file to keep his hooves down, he rarely went on made-up roads so didn't need shoeing. His feed was pretty much the only expense, and the odd bale of sawdust in bulk from Scats. All his equipment was second-hand. Before we moved to the house with the stables, he lived in a large disused garden shed, I laid a brick floor for him. The largest expense ever was having him gelded.
He provided all the manure I could possibly want for my veg patch, I sorely miss that. Endless entertainment for the children, and he was my running companion every morning around his field - hence the wide stick. Just occasionally he would try to head me off and I would use the stick as they do in martial arts.
He only bit people if they wore sparkly rings. I always warned people I hired to feed him while I was away, but they never listened. I think one girl's parents were about to sue me, until I asked to see the instructions I gave her and pointed out 'Never wear rings'. As it was underlined several times, she had no excuse. She had said Yes, she had worn rings when I asked, clearly she hadn't even read my instructions.
If you are thinking that feeding the horse while on holiday is another expense, I also had three dogs, three cats and a dozen chickens!