Singapore's Changi International Airport has been ranked the top airport in the world by Skytrax for six years running.

It has impressive amenities like a free movie theater, a butterfly garden, a rooftop swimming pool, and 24-hour spas, but it's the airport's cleanliness and efficiency that the average traveler will notice most.

On a recent visit, I went from check-in through security to my boarding gate in 15 minutes and found the airport's new Terminal 4 to be thoughtful, pleasant, and relaxed.

I'm the kind of person who usually hates spending any unnecessary time in an airport, but I'd happily get to Changi early on a future flight.

For six years in a row, Singapore's Changi Airport has been rated the top airport in the world by Skytrax, a UK-based customer-service reviewer that has been ranking airports since 1999.

That lofty ranking was most recently based on 13.73 million questionnaires completed by customers over a roughly six-month period. Skytrax ranked more than 500 airports.

But while traveling around the world as Business Insider's international correspondent, I was left wondering: What exactly does "world's best airport" mean to the average traveler?

In Changi's case, there are a lot of flashy amenities — a free movie theater, a butterfly garden, a rooftop swimming pool, and 24-hour spas are just a few. Still, I wasn't sure what to expect. In general, airports are hellish, frustrating places. Tolerable, at best.

But over the course of three trips to Changi Airport, I found that the airport lived up to the hype. The amenities dazzle if you have the time to enjoy them (as someone who is perpetually late, I barely did), but it's the airport's cleanliness, efficiency, and customer-centric approach that sets it apart from nearly every other airport I've been to.

At Changi's Terminal 4, which opened last October, it took me 15 minutes to go from my taxi drop-off to the boarding gate. For someone used to loitering in interminable security lines at New York's John F. Kennedy International Airport, Changi was a revelation.

Here's what it was like: