Been enjoying the R39S handheld alot. I end up playing games alot more games on it then I do on my PC, eventhough playing the same games on my PC would be technically superior (better controller, better screen, more accurate emulation, etc).
Thats probably because I associate my PC too much with working, webbrowsing and watching youtube videos, so its harder to start up a game and keep playing it as long.
I only play 2D games on it, and its almost perfect for any 2D game. Runs SNES, GBA, DS, and even some 2D games on PS1/N64/DC fine.
It can run quite a few 3D games on N64 and PS1 if you crank up the powerusage, but the emulation is buggy and it drains the battery fast so I just don't consider it atall. I see it as a 2D games only handheld for me personally. It has good battery life if you force it into powersaving mode.
The sharp-bilinear filter fixes any problems with the screen aspect ratio and resolution, or need for integer scaling. Which it had better batterylife during sleep mode, or booted up faster. Also appreciate Retroarch more now that ive used it on a handheld.
The only thing I actively dislike about it, is how loud the shoulder and start/select buttons are, they really make me not wanna click them atall, atleast I can map L/R/Start/Select to X and Y for some systems. Even mapped them to the analog sticks because I hate how loud start/select are THAT much.
I bought a second one to give to my brother, I think he would actually use it alot if he had one, and its only about 30 euro.