I've been to Busan. I've been from Cheongsapo to Yeongdo and Dadaepo.
Busan wasn't as humid as I thought, so it was okay.
It was hard to carry a 10kg bag, but it was fun.
Busan's cityscape seems to be on par with Seoul's or even better.
But the traffic is hell, and it's all hills and mountains, so it's hard to get around.