While it's true that Unicomp have purchased all the rights and equipment to make Model M keyboards, the quality doesn't seem to a candle to the original. I managed to break two in the span of two years. At which point I gave up on them and simply built my own. This could just have been catastrophically bad luck. Or like Linus says in the video, maybe it has something to do with their version being based on the newer, cheaper Lexmark version and not the IBM original.
Model F was a very interesting keyboard. I was rather fond of the 24 function keys on mine. And I now regret not having taken mine with me when I moved out at age 18.
The model M got progressively "cheaper" throughout its lifetime. Mostly, metal was replaced with plastic. The keyswitches and keycaps are still top quality.
What Unicomp makes today is a mid-90s version of the model M. It's not the best ever made, but it's still pretty good. However, there are other keyboards around that are also pretty good.
I have a Unicomp, and my roommate spilled water on it once, which caused a bunch of the keys to not register and required a rebuild (which cost almost as much as a new keyboard).
I use both (model M at home, Unicomp at work) and while I've not had any failures, it's clear that the Unicomp is made of cheaper materials. One example is the case itself - the Model M's case is made of thick ABS, while the Unicomp is made of thin polystyrene. As a result, the two keyboards feel different - there's a a resonance from keypresses on the Unicomp that's almost entirely dampened on the M.
Like every piece of anecdata, it varies. I have a unicomp with PS/2 adapter from ... at least a decade ago; before they even made one with "Windows" keys. Maybe longer. It works as good today as it did then.
What I've heard is that Unicomp owns the actual original molds and such, and keeps using them, even though they're deteriorating. So I guess it makes sense that older Unicomp hardware is better. (I'm not sure how accurate that is, but it's what I've heard.)
Model F was a very interesting keyboard. I was rather fond of the 24 function keys on mine. And I now regret not having taken mine with me when I moved out at age 18.