The short of it: 6 out of 8 Nations
The long of it: I pretty much agree with everything Sean says here so just give it a look-see for yourself. It really isn’t a kid’s movie, it’s an adult’s point of view of what the turmoil of being a kid was like.
And yes, if you were a younger sibling, you would probably connect with this film even more – especially if the gap between your older sibling and yourself wasn’t that much. Being 3 years younger than my sister, the gap was short enough that we played games together as little kids and what not; but it was big enough that when she started growing up, I was still stuck at child mode and could not understand why she wasn’t my old pal anymore.