And all the same colour and size. I've never handled dollars but I'd imagine that would be annoying. I like that I can tell a 20 and 50 euro bill apart even when I'm totally drunk.

I come from a funny-coloured-currency country but lived in the USA for a while. And, yes, it's very confusing dealing with the money there. You'd think you had loads of money in you wallet because it was straining your pocket, but it was just 25 one-dollar bills. With coloured bills, a person naturally tends to organize them a bit so you can tell at a glance whether you have enough money for lunch or not.

The other thing is that bills feel sort of greasy or dirty. I'm not sure I can quite describe that, though.

We used to have paper bills where I live but now it's plastic ones. They took a while to get used to because they are stiff and hard to organize. Then again, I almost never use actual currency anymore. It's all payment by phone or card.

(Edit: spelling)