MIST was actually his second game A Tale of Eden was his first. I would put this game between the first and second game in terms of quality. Also, I don't know if he added anything new because I didn't finish it, but one thing is for sure, that he constantly improving is not true, look at my example of animation from my previous post. Good animations and/or Story are very important in a adult game imho and MIST had both: great story/characters and animations. So the second game is the magnum opus of this dev so far. So my advice: try MIST, since you haven't played it yet, then you'll see the difference.
No. there is an overall objective improvement in the dev's technique between MIST and CoM.
Now, I've played both games and loved MIST, but to call it his 'magnum opus' when when he's really only made 3 games is... exaggerating a bit.
Plus, Most would consider MIST his first real successful project anyway.
If anything, MIST was more inconsistent in its presentation than CoM is.
It clearly showed the growing pains of what making a fully featured game entails.
CoM is very much more consistent from the get go. Is it perfect? No. Is it finished? Also no.
Is it objectively better or worse than MIST? Irrelevant. Opinion is subjective by default.
That said, if you don't have the bias filters on, then yes... the dev is objectively improving on his craft and it shows. Do NOT let your love for an earlier game blind you to reality.