I've only ever had to wear a gym uniform, but amongst the three I had, two were literally the most poorly designed garments I've ever worn. Middle school had these two-layered t shirts made of incredibly thick fabric, elementary school had proportionally awful everything made out of cheap, stiff, itchy fabric.
The material, the colors, the blandness, especially how itchy it was. The worst was I had to wear school colors, it was a horrid mix: blue and orange everyday. It was like everyone was walking fluorescent light bulbs.
I wore school uniforms all through Primary and Secondary schools. When you're wearing one, you don't generally think about it too much. By the time we were in 5th and 6th year, they relaxed the rules slightly. You didn't have to wear the top. So a shirt / tie with slacks and shoes was acceptable.