I didn't order the chrome line interior... I guess it didn't appeal and for me it doesn't add anything.
The detailed options list says you get chrome surrounds for air outlets, gear lever, hand brake lever cover, door speakers, central instrument and door handles (half ring).
OK, I just played with the designer on the mini website and paid attention to those details... the added chrome is really quite subtle... it's a ring around the base of the gear lever and the very end of the handbrake where the button is. I might have been tempted by a nice metal gear lever knob... but this isn't it.
I did order the chrome line exterior though... this replaces the aluminium look front grill and tailgate handle with chrome versions (and a couple of other surrounds).
If it was me I'd look at which other options are around the same price and then weigh the choices...