Dangdang is a fun unserious song, i love it tho. It’s catchy and easily stuck on your mind. But the rest of the album is good too. Give it a listen. My fav b-sides are Starry Sea and Save Me. If you want to know about Moonbyul solo i would suggest you start with her iconic Eclipse from her Dark side of the Moon mini album than move on from there. Mamamoo have many good songs. You can check them out too.