One thing I'm noticing is that buying retro handhelds can very easily become addictive. Few people stop at one. They're cheap enough to be almost impulse purchases, they have enough differentiating features to make it easy to justify "just one more device", and yet you end up playing mostly the same games.
I find myself watching Russ's video here and thinking "hmmm, I really need one of these... you know, for Sega", while trying not to make eye contact with my MM+, RP2S, modded Vita and modded 3DS.