Likes: The dished profile of the keys, which more naturally reflects the arch your finger tips travel, reducing the overall need for movement. While common among split keyboards, I also really like the thumb keys. I use emacs, so it's nice to have easy and comfortable access to all the modifiers.
Dislikes: Actually being split would be nice.
The biggest advantage is its ergonomic design. It's a fixed split with vertical keys and good palm support. And main key clusters are concave/dished and it feels more natural than flat or normal curved designs.
I also like that it is fully programmable. You have all the popular layouts by default and you can add your custom layouts, macros, remaps, and etc all onboard on hardware. So you don't need a software to customize it.
It took me two weeks to get used to it even though I was doing touch typing for a long time before that, and it took me a month to get back to my typing speed.
I've done some remapping to make it more comfortable for coding.
It's definitely not an ideal keyboard for gaming unless you make a dedicated layout for gaming.
Likes: Same as above. I'm impressed by the overall comfort of the keyboard, as I can use it all day with no joint pain or stress. It's hard to imagine a more comfortable and healthy keyboard for the long term.
Dislikes: The lack of a numpad is troublesome sometimes, but it makes sense for a keyboard with such a radical commitment to ergonomics. Gaming with it can be challenging, requiring me to pull out a different keyboard. Also, this might sound really petty, but the sound is less satisfying compared to my previous Fission MX Cherry Brown keyboard. The clacks reverberate through the large hollow chassis with a lower pitch. I even put a sock inside the keyboard to dampen the sound, which was only partly effective.
Likes: The ergonomics! This keyboard is really comfortable to use for long stretches. It has reduced the strain of using the computer. Thumb keys are great.
Dislikes: It took me a while to get comfortable with it, especially for programming. I had to really focus on it for a while, but it was worth it! Also, as mentioned earlier, it's not great for games. The placement of some of the modifiers makes it difficult for some shortcuts, but you can always customize/reprogram it.