If you're running Android then chances are you're already using much more up to date emulatiors than in OD, especially if you use Retroarch. Lower your expectations.
I'm no fan of retroarch. I get better performance using individual emulators than I did when I tried the retroarch cores. Especially CPS2, it ran really slow if at all. And getting RA to work at all was a nightmare compared to the other emulators.
It's pretty incredible on PC and iOS. On PC it's a bit hard to setup, at least the way I did it with several configs, but works seamlessly with frontends, launching in windowed fullscreen. It's nice to be able to use BSNES and Nestopia in libretro core form, since the stand alone versions of those emulators have annoyances (input lag in Nestopia, ROM folders spamming my Roaming folder with Higan). I can put my saves, firmware and savestates wherever I want. And everything is simplified vs. having so many individual emulators to keep track of when looking for updates. In general on Windows is runs pretty well; I can use everything at fullspeed except BSNES and Mednafen-PSX on my oldest PC, which has a meager Athlon XP running at 2Ghz and a Geforce 6200. I do have to turn off shaders and the input lag reducing hard sync for that PC though.
I'm not really interested in using it for arcade stuff on PC since MAME is more accurate than FBA and supports so many more games. I tried a Neogeo game on the iOS version and it ran fullspeed, but I forget if I tested any CPS2 games or not.
On iOS it has a simple to use native cocoa based UI. You just have to know where to put ROMs and firmware for that port, then select a ROM and core to emulate it and go. I had a pretty easy time mapping inputs to my iControlPad too (though the input lag with that pad still sucks). Unfortunately I can't get fullspeed on SuperFX games or GBA, but everything else runs great on my 4s. Supposedly A6 powered devices like the iPhone 5 are fast enough for SuperFX and GBA.
I'm sure we'll get some great emulators for the Zero in time regardless. It'll be interesting to see how much accuracy can be squeezed out of the device while maintaining fullspeed. It'd be cool if we could run Mottzilla's BS Zelda patch, for example, which requires decently accurate timing to work. I can only run it properly in SNES9x 1.53, SNES9x-Next and BSNES Balanced or Accuracy (the ingame timer goes crazy and ends the game in BSNES Performance, surprisingly).