Pusan Circle 18R is a pain, but mostly because of company "procedures."
Not to mention the hills. It works to TERPS standards, not PANSOPS. At 2.3 miles, you're just inside the highway. Go outside it and you're in for a whole load of hurt at night - as an Air China 767 found out in 2001 when they didn't appreciate the difference between the circling minima for the two standards!
The big problem with PUS 18R is if you're using it, it usually means you have a 30knt plus quartering tailwind which makes the approach a challenge. We have Kathmandhu and Pusan on our network and I'd rather fly into KTM than the Pusan circling approach at night.