It shifted from "pretty good" to "multi-day" for some users.

It became fanless, meaning it stayed silent even under heavy work.

Thinner bezels and more brightness.

At Best Buy, this turned the MacBook Air from a "safe choice" into a "powerhouse choice." The Lineup Today

When Steve Jobs first pulled the MacBook Air out of a manila envelope, it was a luxury niche item. It had one port and a high price tag. Over the last decade, however, it morphed into the "college student's uniform." If you walked into a Best Buy in 2015, you’d see rows of silver aluminum laptops with glowing logos—the quintessential Air. The Silicon Pivot

You can often find "Excellent" condition Airs for $150 off retail price.