This is an "in addition to" answer, as BlackCat's answer has good points, but I started writing a comment and moved to an answer due to length.

So, the first extra issue is also sensory overload and nuisance. Basically, human society is built for human hearing ranges. There are some things that will have undoubtedly ultrasonic noises that might be strong enough to cause nuisance in animals that can hear them. Some areas might be positively painful for any creature with that kind of hearing range to go into and there might be certain sounds that an individual with that hearing just could not cope with, leaving them rolling around on the floor in agony while people look on in puzzlement.

Equally, it might cause a lot of nuisance if you could hear every mouse squeak and suddenly realise your building is infested with mice you can hear behind the walls or your garden is a major hive of nighttime wildlife activity crossing through and around. It might affect your sleeping, or you'd just look odd, suddenly swiveling to follow sounds that no one else can in a conversation.

With a different hearing range, there's also the issue of responding to sounds. For example, it's been said that cats respond better to women than men because men have lower pitched voices and therefore are harder to hear. If that's true, then that would have a significant impact on the social functioning of your person with cat ears.

However, there might also benefits in some ways. For example, there are mice on the London Underground which are supposedly a different type of mouse because their ultrasonic squeaks are tuned such that they can speak (or should it be squeak?) quite clearly to each other even over the noise of tube trains, which are quite load and deafening at the best of times.

There might also be an adjustment period while the person gets used to things, especially if their hearing is more directional due to the ear-turning thing, and everything might be overload at that point.

While that's not all, the human would also have to deal with suddenly having more body-language with animals, particularly cats, who use ear position as a way of communicating feelings. They'd have to be careful about how their ears are poised if they're trying to deal with a cat especially.

This is an "in addition to" answer, as BlackCat's answer has good points, but I started writing a comment and moved to an answer due to length.

So, the first extra issue is also sensory overload and nuisance. Basically, human society is built for human hearing ranges. There are some things that will have undoubtedly ultrasonic noises that might be strong enough to cause nuisance in animals that can hear them. Some areas might be positively painful for any creature with that kind of hearing range to go into and there might be certain sounds that an individual with that hearing just could not cope with, leaving them rolling around on the floor in agony while people look on in puzzlement.

Equally, it might cause a lot of nuisance if you could hear every mouse squeak and suddenly realise your building is infested with mice you can hear behind the walls or your garden is a major hive of nighttime wildlife activity crossing through and around. It might affect your sleeping, or you'd just look odd, suddenly swiveling to follow sounds that no one else can in a conversation.

With a different hearing range, there's also the issue of responding to sounds. For example, it's been said that cats respond better to women than men because men have lower pitched voices and therefore are harder to hear. If that's true, then that would have a significant impact on the social functioning of your person with cat ears.

However, there might also benefits in some ways. For example, there are mice on the London Underground which are supposedly a different type of mouse because their ultrasonic squeaks are tuned such that they can speak (or should it be squeak?) quite clearly to each other even over the noise of tube trains, which are quite loud and deafening at the best of times.

There might also be an adjustment period while the person gets used to things, especially if their hearing is more directional due to the ear-turning thing, and everything might be overload at that point.

While that's not all, the human would also have to deal with suddenly having more body-language with animals, particularly cats, who use ear position as a way of communicating feelings. They'd have to be careful about how their ears are poised if they're trying to deal with a cat especially.