I just took the Praxis II in Spanish: Content Knowledge and Praxis II: Language Production Skills.
Get the ETS Official study guide. It is worth it. It was very helpful in preparing me for the exam.
There is a lot of cultural items on the test that you need to know--mainly geography, cultural nuances, artists and writers, etc. Most people felt they didn't do well there. You have to listen and be able to pick up on errors by hearing them as well as listen to native speakers. It basically includes many of the same skills as reading and writing from the Praxis I applied to Spanish.
It wasn't a walk in the park, but I felt very prepared generally for what I would face on the test since I had practiced so much with the study guide. We'll see if my score reflects that. .
Good luck! - Eduardo