I have raced many Formula 1 circuits over the years -primarily via the awesome PC game, "F1 Challenge '99-02" which was developed by Image Space -which company also developed rFactor.
I'm assuming that IF the Mandalika Circuit (Indonesia) IS a 'real-life' Formula 1 circuit...that it is a somewhat 'newer' circuit, since I've never heard of it.
The design of the circuit itself is decent but quite 'generic' and lacking in any originality and personality to truly distinguish it from other Formula 1 tracks (no fault of the modder who re-created this track). It would've helped if this track had a significant amount of elevation change to add some 'flair' and more of a 'fun factor' for racing it.
It also doesn't help that the circuit itself isn't of that great graphical quality and textures. Not too bad but definitely could be improved upon...