The raspi is sort of set and forget. It does take a little while to upload the ROMS and then map the buttons for each controller. I just used a logitech ps2 style controller so it would work for all the systems. But since I set it up I haven't had to make any settings changes. I think I only used a keyboard once during set up and never again. It's also cool because you can connect it to wifi and download all the game genie/Pro action replay/gameshark cheats, so in game you just pull up the menu and enable any cheat you want. It plugs in via HDMI and it's so small you can leave it almost anywhere. The basic cana kits on amazon are pretty good. I just got the one that comes with the raspi chip, power supply and basic see through case.
I have the N64 everdrive, and I love it because i can play on my original console with all the original hardware on a CRT. Also, N64 doesn't emulate well on a raspi.
But for all the other retro consoles, I'm super happy with the raspi. I do have a Retron 3, and a few original and multi carts for each system, just to get my favs on a CRT for nostalgia. But overall, for HDMI compatibility and ease of use I totally would get rid of all carts and hardware for a raspi. Save states are awesome too haha.