This mirrors my experience when I visited: incredibly hospitable, polite, and outgoing people.
As a US passport holder with no relation to Iran or Israel, it was easy enough to visit, although you are under the watch of your state-sanctioned minder the entire time as the author eluded to. Going through immigration on arrival, I was detained for about an hour while they presumably were examining my documents, but every encounter I had with police was fairly cordial if not a bit unprofessional.
Once inside, it is indeed a vibrant place. Tehran has a booming nightlife, and outside the gaze of the religious police people were living quite freely (especially in the Armenian or jewish communities). It seems they go to great lengths to do everything as privately as possible, as to not attract the attention of the morality police, allowing them to save face. Young people were quite adamantly secular, and apologetic for their theocratic government. You definitely get the impression that citizens feel the government doesn't represent them at all.
I'm not sure I plan on returning, but I'd certainly encourage curious people to visit as there is a lot worth seeing.