The unique UX of the site, driving around in a 3D car, is what makes this site go viral on occasion. If it were "good" UX, e.g. a standard portfolio site, no one would care and this guy wouldn't be as well known as he is. Therefore the UX is good.
But my point is that, it's not bringing in a new paradigm of UX that you'd want to immitate.
Though maybe it could if others started making "video games but it's just navigating through a website as you play".
As a portfolio to demonstrate your three.js skills for web game making it's really good.