Less road presence.
clearly you haven't passed one yet! i drove past a mk 5 in black today. while in my mk 6 in black. no comparison, and i love the mk 5. the mk 6 is far more standout, particuarly from the back. i could feel the jealousy from the other side of the road 
The Mk5 Gti front was easily identified by other drivers.
The Mk6 gti front looks a little too much like a normal granny golf.
The huge and ugly rear end of both cars is nothing to be proud of.