Having experienced this myself, it was an overall negative experience. But I've also met people with a similar experience who seemed to have a good memory of it.
I think it depends a lot on your kid's personality. I was a quiet, introverted kid who was far ahead of my grade level. I wasn't really interested in sports, just computers. I did not fit in well at new schools and it took me a while to develop friendships. That got worse as I got older - starting at a new high school was particularly challenging.
So now I'm a strong believer in providing a stable environment for my kids. To the point where I think parents who move their family around for themselves are being a little selfish.
As others have said, I think it depends on the children's personalities and parenting style. There are definitely things we could have done better. Our children's specific stories:
Youngest is extraverted, confident, and resilient by nature. I'm pretty sure the trip was a net plus.
Middle has anxiety and couldn't get counseling or treatment in China, and the anxiety developed into a pretty severe disorder. (In treatment now in the US.) But she also gained perspective on different cultures and approaches to life and has friends around the world. So some good outcomes, some bad.
Our oldest is introverted and thoughtful, but she's slow to recover from setbacks, and there were plenty -- especially academic -- from living abroad. She's also very slow to make friends. Probably a net negative for her. I think she would have been better off staying in one place. But maybe she'll be okay. Grandma tells me not to worry.
I was uprooted from one country to the other as a kid.
Pro is that I can pass as a native both in the US and France.
Con is that I don't feel at home in either place; to my American friends I'm the French guy, and to my French friends I'm the American guy.
Overall I think it's mostly positive though. Certainly wouldn't have bad the breadth of experiences I've had otherwise.
There are also deeper questions, like whether I should raise my kids in the US, France, or someone else altogether- but this won't be an issue for another while.
I went through this - it definitely affected me, but I wouldn't call it a negative.
It wasn't so much the living away from home (we were overseas for 2 years when I was 10 years old) it was the return - the shocking disparity between how I now saw the world, and how my peers (who were frozen in time in my memory) saw things. It forever separated me from them in ways they could not understand.
In hindsight, it was one of the best things my parents did for me - compared to most of my home-grown peers, I adapted faster to new situations and had little difficulty adapting to life as an independent adult - in my opinion, thanks to the expanded perspective I gained when I was younger.
YMMV, but IMO, calling it "challenging for a child's social development" implies a negative, but it really depends on what your goals for that child's development are. It's certainly an experience I'd like to repeat for my own children if I can make it happen.
I've seen other research with similar findings. Having moved cities/provinces three times in my childhood (granted within one country) I have to say that it doesn't seem it was tough on me, but I know people who say they wish they hadn't been moved so much. Another part of it for me is that I really like where I ended up; and importantly, I gained all of my social skills after moving to my final childhood municipality, so I associate it with social success.
Our children's experience was very much tied to their extraversion. The most extraverted is doing the best, and the least extraverted has had the biggest net negative outcome, in my opinion.
