erm... well, its spanish, but as the language has been around here for about 450 years, it has adapted and modified troughout the years. this has happened all over latn america. you can say that the countries that speak "spanish" speak their very own language, albeit based on spanish, because sometimes the differences between one place's spanish and the other is so big that you wont understand wtf the other dude is saying. its very curious. cultural context also has a lot to do with it, so yeah, you can say I speak mexican, or mexican spanish.
Cano