I have raced on the Malaysia Sepang circuit, on my PC, many times -on the PC game which I used to own years ago: "F1 Challenge: '99-'02. In my opinion, the Sepang circuit is easily one of the most underrated and best Formula 1 tracks (though I've heard that it is no longer on the Formula 1 season) that exists, and also one of my favorite of all time:
It is a modern, very 'un-claustrophobic' (wide open) and stellar track which is comprised primarily of medium and high speed turns -many of are quite varied, unique, and somewhat challenging- and also some elevation change.
The F1 Challenge version of the Sepang track was superbly rendered: Gritty, bumpy, furiously intense and exciting racing -- challenging but not too difficult.
My opinion is that this version of Sepang for rfactor does the track justice:
The graphics are great throughout the circuit and in some or most ways exceeds the graphical quality of the F1 Challenge version. Grand stands and other nearby track objects are very realistic looking and colorful. If you veer off-road into the sand which surrounds the track, you will have a hard time getting out, which is a realistic touch. The surrounding countryside and trees are great looking and highly reminisce of a tropical setting -such as Malaysia.
Though I prefer the actual grittiness, slippery-ness, and bumpiness of the F1 Challenge version of the Sepang track surface -- this rfactor version is still very very well done. Great job.