It's a hard question to answer, since I'm not that familiar with it and not too much news is available to us, but thanks to sites like Airliners.net and online communities such as this one, we find out more and more about it. Bulgaria, like my home country, Romania is going through a rapid change in infrastructure / economy / culture and trying to integrate itself in the EU. I assume that there are a lot of folks there who are resistant to change and probably would like the "old school" ways that were present during the Soviet / Communist times.
From the outside, I see that a lot of Europeans go to Bulgaria in vacation. I have a lot of friends in Finland who visit Bulgaria every year and the low-cost market is really expanding. I think it's going in the right direction but not as fast as it should be. We'll give it some time and I'm sure eventually it'll be where it's supposed to be... along with Romania and other new EU states.