I'm not an expert on the breed but have owned a few over the last 4 years. We currently have 10 cows. Most of what you read on web pages about them is true: Unique appearance, hardy, good foragers, disease resistant, excellent mothers etc. As long as you're realistic and realize they'll never compete with conventional beef breeds for growth and weight for age. I have a lot of relatives who are full time cattlemen. They think highland cattle are a joke and they're always telling me to sell the hairy yaks and buy some real cattle. They'll grow slowly and if you take them to the saleyards you'll get smashed. That said you can still make a few bucks from them if you sell beef direct to the consumer. There are some highland breeders here who also make income from their hides and horns as well. What they won't tell you on breed webpages is some of the problems. The biggest problem is that most people who buy them and breed them don't know anything about cattle (like me). Compounding this is they're fairly rare which means nearly every animal is allowed to breed. You'll see a lot of animals with poor feet and structure being as breeding stock. Like every breed there are also breeders that sell exceptional animals.
We love them but we're not into cattle to make money. It's a lifestyle thing for us.
Andrew