A couple I am friends with in the UK had it. He got sick for about a week then started feeling better, but she has been sick for months and is still weak. They were not admitted to hospital so this is still considered a mild case, but it has been quite incapacitating for her. They are in their 40s with young children who didn't seem to get sick (or only got sick very mildly) from it.
My uncle and aunt, who are in their 70s, also say they have had it but it did not hit them as hard. I don't know that their cases were confirmed though. They may be mistaking another illness for it.