I travelled twice during Ramazan, and I didn't find it too hard to cope with. The hardest part may be not to drink, as for the few next years Ramazan will be in the hottest months. Even though tourists are not forced to fast, you would probably feel uncomfortable to drink or eat in front of anyone. Good thing to know, buses and savaris stop at noon at road restaurants and most travellers enjoy a meal. Hotel restaurants are indeed opened at noon, especially in big hotels. As Amir said, grocery shops are everywhere so it's very easy to buy fruits, chips or whatever, you just have to go back to your hotel room to eat... All transports, shops, sites are opened as usual, but trying to get a taxi just before sunset can be very difficult!
As for police control, I wouldn't be too paranoid: I didn't know that Ramazan had just started, and when I exited the bazar in Damghan, on a crowded street I lit a cigarette, I passed by a policeman who looked at me but said nothing. The owner of a grocery shop, a very friendly and warm guy, waved at me to tell me that maybe I shouldn't smoke on the street and invited me to finish my cigarette in the back of his store! I guess the policeman had idetified me as a foreigner since I had been roaming all around this small town for the last three days.
Ramazan is actually an interesting time to visit Iran. I was surprised to see that many people are actually "cheating": if you go in parks you will see a lot of people hiding behind their newspapers chewing sandwiches; even in bazars you can spot people sipping tea in their shops as long as they are not on the main streets...