I got mine today in the afternoon, and I've been enjoying it ever since. I'll post the pics soon, I'm also working on recording videos of my compatibility tests. I just recorded every SNES game I have, NES is tomorrow morning's project. For now, I'm going to give my initial review.
I love the packaging. For once, an unofficial product neither immitates the real thing or looks so generic that you can't tell what it is. There's a definite style and it has a fitting logo. Mine came still sealed on both sides with those clear plastic circle stickers, easily peeled one off and folded it inside the cardboard. It states that Retro Duo is trademarked... but not by who >_<.
The controllers are indeed second-rate. On both of mine, it seems slightly harder to press up or down, but the buttons seem fine. When inspecting, they push in a bit far, but they're fine for playing. And yes, they got the convex/concave buttons right. However, I don't get any turbo in NES, with either included pad or my original SNES pad. Some have complained about them being clicky, but I don't mind that, especially on the triggers.
The manual is obviously written by someone who DOES have a grasp on the English language, but some of the points are a bit humerous or odd. I'll scan it tomorrow.
SNES carts go in with minimal force, but I can feel them go down. Removing them is actually difficult, and requires a good bit of force. NES goes in the same, but requires a bit less force to remove. Still, it has a good grip.
The most important point I want to make is how odd it acted at first. I initially only plugged in the audio and S-Video. The first game I tried was Super Mario World, which started up fine. Sound was good, picture was very crisp and looked MUCH better than on my real SNES over composite. Once I entered a level, the whole picture had a "shadow" starting down and to the right about 1/3 of the screen. Next, I tried Star Fox, which was fine, except for big squares of wrong colors that came and went. Skies were blue though. Next was Megaman X, which started up fine until the opening level. The green highway was gray. Last was Chrono Trigger, which also had gray areas, but they were on lots of different things. No sprites, just backgrounds. At this point, I decided to try the composite cable, and I plugged it in so BOTH were active. Problem fixed, beautiful image. I unplug the composite cable, and the color stays proper. Retried the other games, same thing. SNES is perfect, just needed to warm up or something weird like that.
NES looks the same as real hardware on my TV over composite, lots of static trails and a big vertical bar of gray down the middle like a translucent shadow. S-Video is black and white, but it's a much clearer image without the distortion. With both cables on the same input, the picture is clear but the color flickers and makes rainbow effects. Also, the whole screen has light vertical barring.
I'll post pictures of all this tomorrow, as well as edit and upload my playtest footage. All things considered, the Retro Duo was definitely a good purchase, and it does not disappoint. I tried it on my old tv, and the NES static smears don't occur, but the vertical barring does, so some of my problems are display-related.
Everything listed is excellent unless specified otherwise
SNES:
Chrono Trigger
Donkey Kong Country
Donkey Kong Country 2: Diddy's Kong Quest
Earthbound
Legend of Zelda: A Link to the Past
Mega Man's Soccer
Mega Man X
Star Fox
Super Mario Kart
Super Mario RPG: Legend of the Seven Stars - Doesn't boot, guessing I have 1.1 or 1.2
Super Mario World
Super Mario World 2: Yoshi's Island
Super Metroid
Super R-Type