I've had Gmail for over a year now, and STILL the only way I can find any old emails I need to reply to is by using their search function.
I DON'T GET their conversation/cataloguing style. I've had more things to do fall through the cracks because of this function (or lack thereof).
Just now, I was trying to work quickly through my obnoxious inbox, and realized I sent three emails out in a row that had the search highlighting still in them. Subtext: "HI! I'm a superbusy, technologically retarded douche bag who doesn't give a shit about you! Hahahah!!!"
God, and I HATE having to go into the address book.
I know I'm supposed to just LOVE Gmail. I do think they do an excellent job of keeping spam out of my sight. But the rest makes my brain bruise.