I have been using this keyboard for six weeks now and despite macOS 12.4 Monterey reporting that the keyboard layout is not identifiable all the key functions appear to work correctly for a UK (British-English) layout.
The Matias keyboard has a substantial weight and sturdy build, much heavier than the type-2 Apple wireless extended keyboard, (with non-replaceable built-in Lithium rechargeable battery) as supplied with the 2017 iMac Pro, and this helps to stop the keyboard sliding across the desktop while the sturdier build does not flex and bend in use, which is an issue with the type-2 Apple wireless extended keyboard.
Key travel is a little longer than the standard Apple keyboard and does require a little more force to register a key stroke but this is consistent across all the keys.
Key response time is a little slower than I am used to with the standard Apple keyboard, this is nothing to do with key repeat speed but probably just down to the longer key travel and the higher force needed to register a key press, having been using the Apple keyboard for five years it will take a little time to get used to this one, in the mean time I just type a little slower to avoid missed characters.
The RGB keyboard backlight might be of benefit in some situations but as this Mac is used for science and engineering applications in a well lit office, and I touch-type without looking at the keyboard, then the backlight is not really necessary and I have not used it apart from an initial check when the keyboard was delivered. Remembering the key combinations to switch the backlight onoff might be an issue for some (Backlight -+ key and one of the number keys together to switch on the backlight and adjust the brightness and Backlight -+ key plus the esc key to turn the backlight off), plus the backlight status is not remembered if you shut-down the Mac at the end of the day, you need to manually switch the backlight on the next time you start the Mac. The backlight colour setting is retained though via a wheel at the back of the keyboard, as long as you don't knock it accidentally when cleaning up the desktop!
Only given four out of five stars because the additional USB extension socket provided is on the right-rear side of the keyboard and if you are right handed and using a mouse you will find yourself constantly colliding with anything plugged into that socket as the device will be sticking out into the path of the mouse when working on a small desktop with limited space. I had hoped to use that socket for the mouse and have one less cable across the desktop but sadly because of the collision problem this just does not work, plugging in a memory stick is also a collision hazard. It would have made much more sense to have had that additional USB extension socket on the back of the keyboard, or on a side-back swivel joint, or better still, had two sockets, one at either end of the keyboard to cater for both right and left handed operator layouts.
Overall though a good alternative to the Apple wireless extended keyboard when working on a small desktop or where the Apple extended keyboard forces the mouse too far out to the right and causes arm and shoulder ache when working for long periods with CAD or graphics applications that require extensive mouse usage.