It should make games look quite a better better on an HDTV compared to using composite/s-video. It's somewhat analogous to watching a DVD on an upconverting player through HDMI versus watching the same DVD with an old player.
I played it at E3. The output is gorgeous, on par with rom emulation on PC. The only thing is input lag. We were playing Super Mario Allstars and there was literally like a full second of input lag. Basically unplayable. We were told it was the TV (which was a huge HD tv), so I was wondering if anyone has heard any other reports of input lag? I'm still buying it regardless because $100 is such a good price, and I'm hopeful the lag was a fluke. You certainly won't be disappointed with the visuals though, its perfect looking.
Purely speculating here (and biased by some hopeful-optimism), but I would've thought the lag would be more prevalent at a big convention simply due to how much wireless interference that's bound to be there from eight billion other devices (consoles, projectors, hands-free phone devices, et al).
I guess time will tell, and that's also one of the reasons that, even though I'm really psyched about the R5, I'm not pre-ordering until I read actual hands-on reviews (although I'm more concerned with cartridge performance, above all else).
I'm using RGB Outs on my Saturn and Dreamcast and Genesis to an HDMI upscaler (not the expensive XRGB either) and its like staring at a giant arcade machine. SOOOO CLEAR and clean. No color bleed or haloing. WWAAAY better than plugging in composite or SVID.
The RETRON 5 should look the same for Genesis. Don't have SNES modified for RGB at the moment
Old TVs had a resolution of 240p. If you prefer the old school "pixel" look, the emulators running on Retron 5 will simply multiply the old resolution by 4.5 times (if you have a 1080p TV). Otherwise you can do advanced blending to smooth out the hard pixels with shaders. Try out some emulators on your computer for a "preview" of how emulated console output looks.
I ran into the same thing when I tried playing some of my old systems on my HD tv. Setting the TV to "game mode" took care of the lag. Every HD tv I have has this feature. They probably just didnt set it at E3.