Just read this on techradar regarding emulation on the Pi 2. Sounds like the nes,SNES, and genesis work great, which is what I want it for. I may take a chance
Up to speed?
How good is the actual emulation? For the most part it's great. Sega Mega Drive/Gensis games run at full speed, as did all the SNES games we tried. There were some visual glitches in Super FX games like Star Fox/Wing and Stunt Race FX, but that's more down to the state of the emulator rather than anything specific to the Raspberry Pi 2 or Emulation Station.
In fact, Emulation Station actually includes multiple emulators for the trickier systems. There are three SNES emulators, two MAME emulators and two N64 emulators on hand to experiment with.

The only consistent slowdown we saw was with N64 games. Many run very well, including Mario Kart 64, but fan favourite Goldeneye 007's frame rate was inconsistent, taking a real dip in more open areas. It's playable with patience, but only just.
There are some games that flat-out didn't run though, sadly including the much-loved The Legend of Zelda: Ocarina of Time. Some retro gaming tinkerers have had better luck than us, however, with videos of it working on Raspberry Pi 2 already available on YouTube.
A lot of retro games look pretty great too. Emulation Station doesn't go overboard with fancy filters to smooth out older games, but you can choose the output resolution for each system, letting you pick between a more pixelated or blurry look.
N64 is a case of various hits and misses, but every other system we tried works very well on Raspberry Pi. It really does make a great base as a retro gaming system. PSX emulation is particularly impressive, seeming virtually perfect with the handful of titles we tried.