I had a Sinclair QL which pioneered the keyboard. It wasn’t great - it was far behind the Acorn BBCs and the Commodores) but it was quite usable.
There was significant vertical travel, and there was variation in the push the key gave back - increasing to a point of no return, then a quick downward movement to the thunk of the end of key travel.
I could type moderately fast on it.
It is the defecal standard though.