I still have a C64 in my basement in case I need a nostalgia kick. A few years ago I set it all up and loaded a game. I was surprised at how slow it is and how bad the game was compared to how I remember it - so I boxed it up again and have no intention of setting it up again to keep my fond memories intact.
I have a feeling many who buy this product will ultimately do the same.
I had the opposite experience. I bought a C64 at a flea market and hooked it up to an old Sanyo TV I had found in a dumpster. Loaded up Time Pilot, Drop Zone, and H.E.R.O., and had an incredibly fun time playing them together with a date.
Sometimes the nostalgia doesn't kick in, and clearly many things were objectively bad in a way that hits differently now. I wouldn't want to sit long nights writing assembly code and battle bad sectors on floppy disks. But I still think it's a great little gaming computer.
I hear you about the slowness, I definitely do not miss it. The good news about retro devices is that games load instantly, and you can save memory snapshots.
As for the games... some are a pain to play today, but others are surprisingly good and the music is beyond cool. Of course, nostalgia is a big factor, but still...
I have a feeling many who buy this product will ultimately do the same.