I had two BlackBerry devices for work, right about the time they were going away. I’d heard the keyboard was good on earlier models but it seemed like the quality had gotten pretty cheap on the later phones. The BlackBerry 10 OS on my last phone was actually pretty good, and probably would’ve kept them in the market if they’d launched it 5 years earlier.
I’m guessing OP means the build quality, as defined by the mechanical and material standards that are needed to recreate the keyboard.