I worked as the Volunteer Coordinator for the Safe Stove Project at Pop Wuj. As I spoke Spanish already I didn't study at the school. The volunteers I work with were mainly student at the school so I heard a lot of talk about the staff, the learning experience and the after school activities. I have to say almost all of these were positive. On the odd occasion were students weren't having a great time it was due to personality clashes which is bound to happen from time to time.
Pop Wuj offers a great medical Spanish program and what ever program you do there are lots of opportunities to get involved in the schools various projects. And, if you're keen to do a project that the school doesn't do they're happy to hear what it is an help out if it's appropriate.