Having driven my 2014 A4 6MT for more than a year, the summary of my gripes is as follows:
--- gas tank is too small, allowing for about 500 kms of driving in winter and 550 kms in summer
--- transmissions ratios are too tall and too widely spaced. Sixth gear is almost unusable below 120 km/h because of weak throttle response. It's only good for inter-city cruising
--- automatic headlight washers are a nuisance. They start each time the windshied washer is used while the headlights are on. Each squirt consumes 250 ml of fluid. A short trip at night in winter can be enough to empty the tank. My workaround: disable auto-headlights, and try to avoid using the windshield washer. When I get to a stoplight, turn off the headlights, wash the windshield, then turn the headlights back on before restarting. After lenghty discussion with my dealer, there is no way to simply disable the headlight washers... They are even on the same fuse as the windshield washer.
--- hill-holder grabs too strongly and must be fought with more throttle than otherwise necessary when starting after a stop on a hill
--- rain-sensing wipers are erratic and can't be turned into a simpler time-delay mode.
--- air conditionning is weak.
--- the 280 km/h speedometer is too tight as usable speeds cover only 75% of the dial. 240 km/ would have been enough.
--- no provision for installing an engine block heater
Apart from these design issues, my A4 has been completely reliable and is a pleasure to drive.