NES: Great
Gameboy: Great
SNES: Great
Genesis: Great
Gameboy Advance: Great
N64: Good – the Shield hardware is more than enough to run the games, the emulators available are the problem.
Playstation/PSX: Great
NDS: Great
GameCube and above: Poor – games are unplayable. (Emulator problem as much as a hardware problem)

There is one problem with the Shield Tablet that makes it a poor choice as a hand held emulator console, the battery life. I was lucky to get four hours of battery browsing the web and playing videos. Using it to play Chrono Trigger for the SNES got me about three hours of battery. The advertised battery life is 6-8 hours. Even more disappointing was that I could plug the charger in and the battery would still drain just from browsing the web/playing YouTube. I thought that my device had a hardware defect and sent it back, the new device had the same problem. If you read the NVIDIA forums, this is apparently a ‘thing’ with the Shield Tablets.

Considering how great the Shield Portable is its such a shame the tablet has these power problems. This one problem ruined an otherwise perfect tablet for me. Very disappointing.

NVIDIA Shield Portable

Below is my quickie rundown of how well the NVIDIA Shield Portable emulates classic consoles.

NES: Great
Gameboy: Great
SNES: Great
Genesis: Great
Gameboy Advance: Great
N64: Good – the Shield hardware is more than enough to run the games, the emulators available are the problem.
Playstation/PSX: Great
NDS: Good. Some lag in parts, but nothing too bad.
GameCube and above: Poor – games are unplayable

tl;dr: The Shield Portable is best handheld emulator console out there.