iFixit's story is a good read if you want to get the full, sad tale of the rise and fall of Apple's laptop keyboards. Long story short, Apple replaced the comfortable, highly-lauded keyboard in the MacBook Pro in the fall of 2016, bringing over the thin, butterfly-switch keyboard it originally introduced in the tiny 12-inch MacBook in 2015. People were pretty quickly divided about the new keyboard's shallow travel and rather loud typing sound, but the bigger issue was undoubtably a reliability one. Keys were liable to get stuck or repeat characters if even a small piece of dust or a crumb got in there the right way, and getting them fixed required taking apart the entire laptop. It was, in short, a fiasco.
Apple tried to make the keys more reliable over a few revisions of the butterfly keyboard mechanism, and it also guaranteed to replace any computer with that keyboard if there were issues even after the warranty expired. My own experience with Apple's 13-inch MacBook Pro from this year is that the keyboard is now much more reliable than previous models I've tried -- but it does seem the keyboard is inherently flawed.
It's thus a huge relief that they've gone back to the scissor-style keyboard design, which means more travel and easier repairability. If you want to get up-close and personal with Apple's various keyboard designs over the last few years, definitely check out the photography over at iFixit. We'll have a full review of the new MacBook Pro soon, but in the meantime you can at the very least rest assured that the keyboard is a huge step forward. Now we'll just have to wait for Apple to bring it to the rest of its MacBook lineup.