I haven't had any issues, but then the bike only has 7500 kliks on it. I love the ABS brakes. Much better then the brakes on my old VFR. I'm confident that in an emergency situation they will slow me down very quickly without locking up the tires.
A BMW bulletin *was* issued stating that "the ABS could be temporarily disabled after a specific set of circumstances involving aggressive brake demonstrations or aggressive rider training." In another paragraph they stated that these circumstances are "not known to occur under normal riding conditions."
One thing I've read about more then once in different bike mags is the fact the bike only has residual braking when the engine is off which might cause a problem when moving the bike around the garage or in a similar environment. Talk about nitpicking. I've pushed my bike around the garage and different parking lots numerous times and never had any problem whatsoever. I seldom need to apply the brakes when I'm pushing the bike, it just stops on it's own when I quit pushing due to some unseen force, gravity I think it's called. When I have needed the brakes, the residual brakes are more then enough to stop the bike.