Generally 100% for educated people, maybe less so for those not well schooled or living in a bubble. Of course, just like with any language, there are regional and international variations in the language that is used, but just remember that English is English. Of course, you can find people anywhere who speak badly and use excessive slang. These people can be very hard to understand even for people living in the same town. At the end of the day though, we all speak the same language - English!