Here are some cities that have only one or very few interesting stations. This page is meant as a supplement to the Metro Arts and Architecture page that shows many of the world's best subway stations and lists cities that foster good station design and architecture.
Like in pop music history, where an artist who has been successful with just one single song is known as a "one-hit wonder", there are subway cities that have only one or very few noteworthy subway stations. Whatever the reason is that those cities have left all their other stations in a less interesting state of appearance, some of those one-hit-wonder station designs are first-class and should not go unnoticed, so here they are...
The transport in the largest city of New Zealand is being upgraded recently. Britomart Transport Centre is the first station that has been refurbished in this process.
Though the overall appearance of America's first subway is not that great, they started to include works of art in stations in 1967 and continue to do so with new stations. Murals, sculptures and other types of artworks have been acquired through donations and art competitions [mbta.com].
Photo [Madhava Enros, madhava.com]: Ornate wrought-iron entrance structure built in 1917 at Copley station.
The capital of North Korea has a socialist-style metro with murals and a grand architecture in a few stations [pyongyang-metro.com], [biglobe.ne.jp]. However, only two or three stations are open to tourists.
Photo [Wooolf, flickr.com]: Platform level of Puhung station.
Zurich doesn't have a metro, but a few of the underground and at-grade commuter rail (S-Bahn) stations have interesting architecture.
Photo [Donald Corner and Jenny Young, greatbuildings.com]: The organic concrete structure of Stadelhofen station, built in 1990 by architect Santiago Calatrava.
Pyongyang