Good/strong identity and musical integrity. Even if not all their songs are to my taste, it's still very clearly NewJeans, which I respect. This is a lot more important than maybe many think, especially in a fast-moving industry like kpop. And when they do their style well, they do it REALLY well.
OMG and New Jeans (should've been longer..) are some of the best song from 4th gen GGs. Hype Boy, Attention, Supernatural and ETA are also great.
Very pleasant and soothing voices/tones. Goes well together with their songs.
They're cute girls and my heart hurts a bit for them for what they're going through. I hope they come out of this together and continue to release music. I applaud Hanni as she's been especially brave.
Also, the way they debuted was refreshing!