I debated on upgrading from the 5, which was perfectly fine and I loved. I made the switch and don't regret it. The shape is slightly different and much nicer in the hande. The camera is a huge improvement as are some of the software updates. My only gripe was with Samsung online ordering. The assistant I worked with ordered me the wrong phone color, not the biggest deal, turns out craft black is pretty cool, even though I loved the blue. Samsungs trade in policy makes it hard not to upgrade.
Compared to Z Flip5, there's no slight dip where the screen folds over. It's a great technical feat. The camera seems to be better than Flip5 but will need to take more pictures under various lighting conditions to confirm.
Yes, the matte finsh is a lot better then the old finsh. But I did noticed my colors on my home screen wallpaper was not as bright as my home screen wallpaper on the flip 5. The pink and blue colors on my home screen was more faded out then on my flip 5. Was that me or was it the phone's colors on the flip 6? But otherwise the flip 6 is a much better phone then the flip 5. So yes, I love this phone! One thing the flip 5 cases Will Not fit the flip 6 phone. So you do have to buy a new case for the flip 6.
I am a Flip fan, I love the form factor. I had the Flip 3, 4, and 5 but the Flip 6 is the best yet. With the improvements, it feels like a true flagship phone.