The body was made flatter and curvier, more like a wedge than the boxy original. This also made the system smaller. The power button in front was replaced with a larger red power switch on top. The reset button was replaced with a larger grey button on top. The NES controller was redesigned to resemble the SNES controller, using a "dog bone" shape.
The color was changed from the grey and black of the original to the two-tone grey of the SNES.
The most notable change, however, was the change from a front-loading design to a top-loading design. Instead of inserting the cartridges into the front and closing the door, the cartridges were placed into the top with no cover.
The system was designed to improve over the original. The games locked securely into the system. The original method would often result in pushing down on the games often, with the mechanism wearing out over time. This improvement also prevented game corrosion. The switch, which locked into position, was designed to replace the button. The button would often wear out and require increased effort for it to stay pressed.
Despite its redesign, all past NES peripherals and games were backward compatible, except for the unlicensed Game Genie, which was made incompatible due to legal controversy.
The NES-101 sold poorly for many reasons. First, it was released at the end of the system's tenure. Most people were already focusing on the SNES, and the Nintendo 64 was already in the planning stages.
The system also lacked the audio/visual hookup that the original had, requiring the R/F hookup that by 1994 was well obsolete.
One minor problem was that the cartridges would often become too secure, requiring extra effort to remove them.
Another minor problem was the lack of an LED power light, although the switch locked into position when on. The switch, when turned on, is also out of alignment with the reset button, making it obvious when the system is on.