Unbelievably rewarding!!

Meddeas: Meddeas has been extremely helpful through the whole process in terms of USA documentation, visas, Spain documentation, etc. Sometimes they don't have all the answers, but in all honesty, the laws and regulations are changing per city in the US pretty fluidly, so I can only imagine managing other countries, too. On top of this, I've heard that other programs don't help with this aspect, so it's definitely a huge benefit. Moreover, Meddeas has given us opportunities to connect with other language assistants through FB pages and our induction meeting. I think the greatest plus side of this program is that you don't have to pay any fee to commit to it, just a deposit that (if you meet necessary criteria) will be given back to you at the end of your term. Going off of that, you get paid monthly and receive a TEFL certificate - again, with no cost to you.
School: The school's truly are going to vary immensely by location, type, grade, etc. My experience has been good so far, but it does require patience. The US system and Spanish system work at different paces. In my personal experience working in secondary, the teachers don't prepare much more than a day ahead of time for a lesson, which was off-putting at times. However, it didn't interfere with my job much as I was mostly taking students out of class in groups to practice speaking for Cambridge Exams. The teachers were the sweetest and truly care about their students' development.
Host Family: My host family is the absolute greatest. I've been blessed with having a family that treats me like one of their own. Aside from teaching the family, I really have bonded with the kids and learned a bunch from them in Spanish, culture, traditions, etc. They'll for sure be invited to my wedding in the future :)