I'm an Atari newbie but here's my thoughts on the Retron77.
I had a Flashback 2 for years, and enjoyed it. Picked up a CIB Star Raiders for a buck at a local gaming shop, and it just sat around as decoration in my gameroom. It always sorta bugged me I coudn't play it. I learned about the method for hacking the FB2 to play cartridges, but it was over my head. A friend agreed to try it for me, and so I picked up a half dozen or so games I remembered playing as a kid while he worked on it. My buddy failed to get the mod right, which was disappointing. However, my desire to play these games was now at an all time high. Looking online, the Retron77 seemed like a good deal, so I ordered it.
It arrived, and I was giddy to be able to play Phoenix and Cosmic Ark again. But Star Raiders didn't work, at least, the keyboard controller didn't. The paddle in Super Breakout was so jerky I couldn't play it. Even got another set of paddles, and cleaned them. Still unplayable. I went to the internet, found this forum, and applied the community update to my Retron77. Still no Star Raiders or Super Breakout. I was really disappointed.
Forum member masschamber was selling a frankenstein half 4 switch half 6 2600 with some common games cheap. I contacted him, and he even threw in some extra clean paddles for me. A few days later I was playing a classic original Atari in my living room, and all the games worked great!
I'm torn, really. The Retron77 image is flawless and it looks amazing... for games that work. The vintage system has all the compatibility but doesn't look great on a modern TV. The rocks in Asteroids looked particularly bad, and the spider legs and even the bullets in Centipede were difficult to see. I'll probably keep the Retron77 in the living room, and move the old-school cool 2600 to the gameroom and hook it up to an old CRT I've kept around. Best of both worlds, right?
However, if I had it all to do again... I would definitely get the vintage system first and skip the Retron77 entirely.