I noticed SHOUTcast's iPhone app no longer exists, so I checked out nine others. Here are the rankings:
1 . TuneIn - shows metadata and large icons of available album art.
2. Streema - shows metadata and medium icons of available album art. However, it puts an icon on your screen that launches a browser page. You can either bookmark it or just leave it amongst your open browser pages, then navigate there when you want to listen.
3. Radio Tuner - shows metadata only.
4. Stitcher - shows neither metadata nor album art.
5. Simple Radio - shows neither metadata nor album art. This is a second, markedly inferior, iPhone app made by Streema - though it doesn't send you to a browser page.
6. Audiorealm - shows neither metadata nor album art. It also has no Favorites, requiring you to hunt for the stream you want every time you launch the app.
7. Radionomy - shows neither metadata nor album art. Also crashes when you click the Play button (at least on iPhone 5S).
8. All Radio - garbage app.
9. OneTunerLite - garbage app.