In the past i'd have had tints to look cool, but now its to keep the interior cool and protect the leather (it gets a BIT hot in the summer) ok it does look good and
protects your modesty if you make a bit of a faux-pax at the lights etc 
but as i've noticed with most people's cars that are tinted they have to drive round with the window open (like some G-star) because its too dark

prats, my old Orion had Dark Grey tints allround (except the windscreen) and that was perfect, not too dark and never a problem with the old bill.