Lot of negative comments here. Some from people who bought one, used it for a while, and returned it. Respect. But many from people who just want to trash it. Ask people who own one, who've spent more time with it than someone who saw it in a store.
I bought a 2018 MB Air a week ago to replace my early 2015 rMBP. I used the rMBP in all kinds of lighting conditions (though not so much outside) and I never found it wanting for brightness. I did a side-by-side comparison of the new MBA with my rMBP and the MBA display is every bit as bright as the rMBP's display (both are rated at 300 nits). Also, the colors are not washed out or otherwise any less pleasing than the colors on the rMBP. I am happy with the display. Sure, it's not as nice as the display on the 2018 MBP with Touch Bar, which has True Tone. But that computer is a lot more expensive than the MBA.
Some are complaining that the 2018 MBA doesn't have mag safe or the glowing apple logo. But neither does any MacBook or MacBook Pro launched in the past couple of years.
Some are complaining about the replacement of the almost universally loved chicklet keyboard with the divisive butterfly keyboard. Again, all current model MacBooks have this. I loved the previous keyboard, too, and thought I'd hate the new one. But after using it for a few days, I don't mind it at all.
Some are complaining about the need for dongles or USB-C hubs. I am living with this thing now and, at least for me, a single hub is all I need (the Satechi hub with USB-C pass-through, 3 USB-A, ethernet, SD-microSD card, and 4K HDMI). Carrying it around is no trouble at all.
Performance is absolutely fine for me. The fan can be noisy but it rarely comes on. Battery life exceeds my rMBP, which is partly because that computer (and its battery) is 3 years old. But I never got more than 6 hours on that computer, even when new, and I'm easily getting 8 on the new MBA.
The new MB Air isn't for everyone. The MB Pro w/o Touch Bar will be a better choice for people who need more power, and for people who don't think the new Air's screen is bright enough.
Haters gonna hate.
But the Air is a good purchase for some of us. For the rest of you, there are some great options for you. I won't criticize your choices because you know what's right for you, not me.