If you're curious about the impact of economic sanctions on Iran, OPEC's newly-released 2014 statistical bulletin provides a pretty concrete look. As the tables below show, in just the past two years Iran's oil exports have fallen by nearly half and the rial has lost a third of its value. If you want to know why Iran is negotiating over its nuclear program, that's the story in a nutshell.
The whole report is here. Plenty of interesting little tidbits there for inquiring minds.