I have been there in 2002 and had an excellent time.
Really nice and friendly people, more open minded than most people outside would think. I was warned not to talk about politics. Wasn't necessary because they started with it. Amazingly, many people don't mind at Israel at all and even some people were in favor of an American war against Iraq, although that war didn't start until almost a year later. Of all those countries through I have travelled, and that's is quite a lot, I think Iranian people are one of the most friendly I have ever met.
Furthermore lots of things to see and to do. I wouldn't hesitate to go back, even these days.
Although I really was eager to make pictures at some airports, I was aware that it could lead to troubles. One time I informed at airport staff at Yazd Airport but they said it was not allowed. In a friendly way, by the way. After reading the previous comments it looks like I could have done better.
Same happened at the former US Embassy in Tehran, the site of the infamous hostage crisis in 1979-1981, were I was walking with my camera. A soldier told me not to make pictures, but with no threats at all.
I wonder if air fares are still that cheap as then. When I flew from THR
to Kerman in the south the only seats which were available were in First Class. The price was the incredible amount of $38 (!) with Mahan Air. Unfortunately no opportunity to fly on the Saha Air 707. Furthermore, lots of Tupolev 154's around although they didn't have a good reputation back then.
At several places it's worth to take a bus however because of the landscape. Especially into the direction of the Caspian Sea to or from Tehran. Bus travel wasn't that bad either. Even with live tv from the World Champions Soccer in South Korea/Japan!
Yes, there is something dangerous and scary in Iran and Tehran in particular and that is the traffic. When you're done with mountain biking, base jumping, bungee jumping, canyoning or rafting, than crossing the streets in Tehran is the real challenge. Crossing Khomeini Square in southern Tehran only for the more experienced ones!
So, I would say have a good time in Iran!