I'm the oldest of two, and I didn't hate it, but there were things that seemed unfair.
1) My parents didn't let me do things that my sister then got to do. I guess they were more wary with me as I was the first, then more relaxed with my sister. For example as a teen they didn't let me go to out to pubs with my friends, but by the time my sister was allowed to drink they didn't have any problems with her going.
2) Like all older siblings, (probably), I was jealous when my sister was born. I wouldn't call her by her real name, I called her Linda.
3) She was always the littlest and the cutest, so she got away with more and people felt sorry for her and took her side.
4) As the oldest, I was always supposed to be the 'responsible one', and was expected to look after my cousins, even though my sister wasn't much younger than me.
5) Because our parents were stricter with me than they were with her, she has very different memories of our childhood!