I have moved a lot across the world during my adult life. Throughout my studies (for internships and semesters abroad), during a 1 year break and now that I work, I have lived in : California, Japan (3 different places), Malaysia, and now Korea. (I am French by the way).
I have also travelled extensively across Europe and South East Asia, but living in a foreign country is a completely different dynamic.
I don't really think of it in terms of upsides and downsides. There are things that are different and they swing both ways:
Different expectations in social interaction
Different views of life
Different styles of communication
Different traditions (I usually love it, but it often hits me hard around the holidays)
Different foods, technologies, entertainment...