For those who are not aware of this, the quality and seriousness of the Iranian students and faculty is very high.   The leaders of the IPM string theory group,  Farhad Ardalan and Hessamaddin Arfaei, are accomplished, distinguished senior physicists.   Mohsen Alishahiha, Mohammad Reza Garousi, and Shahrokh Parvizi are energetic young theorists producing first-rate published work.  Mohammad Mehdi Sheikh-Jabbari, who is now a postdoc at Stanford, will be joining the IPM next year, and is also a first-rate string theorist. As many of you are aware, Iranian students have performed extremely well in the International Physics Olympiad in recent years, and have picked up several gold medals. 

All but one of the above have spent significant time as students and/or postdocs in Europe or North America: the one exception was a postdoc at TIFR. There are growing ties with the Indian string theory community (for those who don't know, the string theorists in India -- particularly those at the TIFR and HRI -- are among the best in the world).

Overall the students' English skills were quite good. English is, of course, the international language of science, and of string theory especially.

The proportion of female students seemed higher than what I see in typical string theory gatherings  in the US and Europe, perhaps by a factor of two.

On the whole, the Iranians I met at and outside the school were mind-bogglingly polite and hospitable.  In two weeks the only reaction I had to my nationality that was other than positive was some guy making a sour face in a cafe.  This is in accord with previous stories I have heard from Americans travelling in Iran. 

I believe the IPM worked quite hard to smooth the way for our visa applications, so we had no trouble getting them (we applied through the Iranian Interests Section of the Pakistani embassy in Washington, DC).  The passport control and customs officials waved me right through when I arrived in Tehran, without any comment.  (US Customs in Boston did pull me aside, of course.)  I don't know if my experience in that sense is typical.