Just finished the original yesterday. I liked it. I'll probably pick up the sequel when it's down to the <$10 price point.
It was very easy to get into and game had the right length. It wasn't repetitive, which is often a problem with flight sims.
It's not really a flight sim though. It was a fairly simple game, but I don't really want to play a flight sim game where you have to land and take off. I think that most of the people who dislike the game come from a more hardcore flight sim background and find the game shallow. Those people are correct, but the game is exciting.