Pretty much everything you need to know has been said. I was there in May with a good 40 rolls of 120, and never had problems shooting anywhere (though I guess the 6 days of 47˚C was a shooting problem, but that was only my fault for going in May!). Airports were fine with film (though didn't want to hand inspect, but ask). I sort of forgot about what was ok to shoot and not to shoot, so I took a few photos inside airports with no problems. Even taking photos of planes out on the runway at Heho. Didn't get hounded by anyone, and actually noticed a significantly larger amound of military and police on the streets in Nepal than in Myanmar.
As a personal note on places, I found Nyaung Shwe/Inle Lake to be the least enjoyable. Touring around on the lake is really cool, but both places are just so touristy compared to the rest of the country, and the people seemed less friendly than everywhere else too.
Also, try to find a copy of The New Light of Myanmar. A nice cheap newspaper full of hilarious propaganda!