Tomorrow I will be picking up a RetroN5 from a local game shop after I bring in some trades. I've been on the fence for a while as I have an Ouya filled to the gills with ROMs. When I feel in the mood to play an old game, I'll link my Wii Classic Controller Pro (or whatever it's called) and go at it that way and for the most part it works for me.
Last night I took my Ouya to my friend's house so her kids could play some classic Super Mario. It was a mix of boys and girls (grand total of 5 playing) with ages ranging from 9 to 4. Overall it went ok but they seemed to have issues with the Pro controller and hand placement. I lost count how many times they accidentally went into the emulator menu. All the while I was wishing I had USB adapters for my original NES controllers as they would have no problems.
Now granted I could get the adapters but by the time I was done I'd be close to the price of a RetroN5 without factoring the price of the Ouya. I like the idea of inserting cartridges in and using my refurbished original controllers. I get that nostalgic feel while the kids will get to experience a combination of the "old school" (cartridges, the original controllers) with the new (HDMI, state saves, etc.).
As a side note, if there's a language patch for it I can finally play Dragon Quest 4 that I got from Queen of Felines way back in the first Secret Santa!
Oh yes, and the 4-year old rocked everyone playing Legend of Zelda. She got the farthest out of everyone.