Mega Man 9 doesn't just look and sound like a NES game. It's going to play like one, and feel like one, to the point where you'll experience some of the glitches and bugs found in old NES titles. Capcom's Hironobu Takeshita has told Gamasutra that players will have the option (literally, via the options menu) to introduce and adjust old-timey NES glitches like screen flicker. Even though new, modern sytems are of course not prone to flickering. Sure, it's the "pre-faded jeans" of the gaming world, but this is the gaming world, not the clothing world, so we're all good.
He Is 8-Bit: Capcom's Hironobu Takeshita Speaks [Gamasutra]