Made in Pongdang is a nice little second-floor pub heading north from Noksapyung Station on the way to Gyunglidan. They also have a location near Sinsa Station (Apgujeong).
They have a good selection of their own craft beers, as well as some nice alternatives and some fancier bottles to choose from.
The vibe is mellow, but it gets crowded during peak times. They seem to have some loyal customers, which says something about what you can expect. They also offer some pub food and possible happy hours prices.