I actually don't mind what Dwight has said, although it does depend heavily on how you want to play. I've been playing for almost 5 years now and what drove me away from the game was the 'spammy' airlines which just dominated every airport, and every route and didn't care about realism or profit. The biggest problem with the game is that genuine players want to create realistic airlines using realistic models and with realistic PAX loads. The moment someone creates an unrealistic airline using unrealistic models and unrealistic PAX loads the game becomes un-fun and boring.
It's a shame but a reality. The few ruin this game for the many.
Unfortunately, as with every other game in the world, relying on a mindset or genuine intentions on the part of players for playability is a recipe for disaster. The game mechanics must be such that this type of players will simply go out of business pretty quickly. It is too difficult to lose money and too easy to idle along in Airline Empires. The real world is a lot harsher -- profits are slim, financing is tough and a down turn or two can easily drive even established airlines into bankruptcy. In fact, ALL the legacy carriers in the US went bankrupt at some point.