Just went to Busan with my friend last month. It was a really sunny day so it was not that cold. We went to songdo beach in the early morning, I think people would not go to the beach in Winter, it was almost no one there but lots of seagull lol. since there was not that much people there, we took lots of beautiful picture there! Also we enjoyed the coffee nearby the beach.

I'm highly recommend to go to the beach in Winter! 

After that we also went to the gukje market and seomeong to enjoy the food and shopping! I think it was really the same just as in Seoul.

Thanks for chingu mobile that I can have interner at anywhere I was!