I wouldn't say it's "much better" than the previous iterations, it's apples and oranges really, and made for two different purposes.
The Retron 5 was meant to play popular old games up scaled via Hi-def on modern TVs and is an android based emulator, while the other clones use reverse engineered chip set hardware and are meant to output to a classic CRT display.
The Retron 5 is not compatible with things like flash carts, light guns and special hardware peripherals like the Famicom Disk System,
all these things are compatible with the earlier Retrons, meaning they can run translated RPGs, homebrews and games like Duck Hunt without an issue.
If someone is after the advanced features of the Retron 5 then an original xbox is dirt cheap and does everything the Retron 5 can do and more, except for having cart slots, and if that is important then you could buy a Retron 3 to play most of your original carts, PLUS an xbox to do everything else, and together you would spend less money than if you bought a Retron 5.
I do happen to like the convenience factor of having all my games fit and run on one system that ANY of the multiclones (even the 5) provide because my old systems can stay in a box preserved from wear and tear, and I don't have to muck about with a metric ton of cables and AC bricks.
As for the Retron 5, it's a nifty piece of kit, but too expensive for what it is.
