It was very good about 5 years ago, and is still quite comfortable.

However I would say that today this has largely been superseded by a myriad of better choices. For the adventurous type there's e.g. Dactyl Manuform. If one does not care so much for the keywell there's Lily 58, Iris or Kyria. For built-in tenting there's ZSA Moonlander, Redox etc.

All of these have better customizability, repairability and portability than a Kinesis Advantage.

Want to try diffent key switches? Use hot-swap sockets.

Want wireless? Drop in a nice!nano microcontroller.

Want to create a crazy custom key layout or macros? You can do anything you want in QMK and flash it to the microcontrollers.