I have an RG353V and I freaking love this thing.
The past few years I barely played games at all. It's only when I got my little device that I noticed how much I liked playing anywhere: On my couch, on my seat, in my bed or during travel.
It really reignited my love of games.
I have some great fun playing Pokémon RomHacks like Unbound or GS Chronicles.
Otherwise I started playing the original Mega Man Battle Network titles for the GBA.