If you just press "up" without typing anything first then it works as you expect. I find ^R annoying if I've already started typing the command and then realise I can search the history (although that's probably configurable).
Once you get used to it, the only downside of up/down history search is when you ever use a shell that doesn't do it and you feel lost.
Once you get used to it, the only downside of up/down history search is when you ever use a shell that doesn't do it and you feel lost.