And minimal they are. The only camouflage to be found on this prototype are on the headlamps, taillamps, and spaces where the side indicators would normally reside. For its mid-cycle enhancement, BMW will be incorporating the side indicators into the mirrors, and the camouflage at the fore and aft light clusters suggests that some new lamps will be incorporated into the design. Don't expect too much to change at the rear, but up front, BMW's "angel eyes" will likely take on a similar (read: squarer) shape akin to what's available on the new 3 Series, trimmed with LED eyeliner.
We won't rule out the possibility of some powertrain tweaks or perhaps even some massaging to the front fascia, but until we have any sort of hard evidence, rest assured this German roadster won't be changing too much in its current lifecycle.