I think this was a big factor in why AIM trumped ICQ in America. ICQ had that "sending mail" icon that took a few seconds (or more) to "send" your message and it didn't quite feel instant.
It was also a ui issue. ICQ originally had an interface which didn't show a running log of the conversation. It was more like sending email with presence indicators and a 450 character limit. Though it also had an IRC-like mode that was rarely used. I remember finding AIM and MSN so different when they emerged as the 'instant' aspect, typing indicator, and running log encouraged rapid-fire short messages and gave a conversation-like feel.
> ICQ originally had an interface which didn't show a running log of the conversation.
The earliest version I remember, before 98a, had a history button that would show the running log on the top of the message box window, which was nice.
The nicest thing about ICQ for me back then was the fact that the message disappeared when you sent it -- it wasn't there filling your taskbar or occupying your mindspace.
