I realise everyone's experience is different but my recent experience was only positive (aside from the mercenary driving).

My greatest relief at leaving Iran was not having to be force-fed any more tea.

I've been mugged, had stuff stolen, and been near-to-death food poisoned when on riding trips; but all in Australia. Got touched up by corrupt officials in southeast Asia but that was nothing compared to the legal robbery of Australian officialdom.

I found Iranian officials non-corrupt and particularly helpful (warning: the tourist cops in Esfahan are building an English idioms database. I added "dingo-ugly" and "pissing-down rain" but many they had gathered were less genteel.)

In my view, Iran was up there with the most user-friendly biker places I've been to (once you get used to dealing with the traffic and crowds of interested onlookers). In terms of shit cops and crime it's certainly got nothing on Cambodia, Lebanon, Vietnam, India etc etc...

A fine moment was outside Tabriz in minus 8 celcius in a blizzard when I was (besides dying) trying to struggle with getting more gear on - a truck pulled up alongside with only a metre or so to spare. Here am I thinking this guy's some kind of dickhead when later, as we were drinking tea in his warm sleeping cabin, he explained (in his ten words of English and well-refined sign-language) that he had seen me perishing on the side of the road and was trying to provide some shelter for me, with his trailer, from the snow-storm.

Iran...shit for some, unforgettably wonderful for me.

cheers
Brett