It took me like an hour to get it working (including all soldering and testing - everything worked just right on first try).
The documentation is really retro, as I remember from that era, so I would just add, that you should be carefull on polarity (is not marked, but can be simply decided from electrical schema on github and that you should use independent 5V source of power, as the USB-TTL convertor is suppose to provide only GND and Rx/Tx, NOT VCC.

You get simple monitor program already installed in EEPROM together with two modules, one just simple test, the other simple tiny BASIC (2.5kB), so you can start playing with it as soon, as you finish the instalation (by using any computer with USB as simple serial terminal - LOL 2GHz 16GB RAM laptop as dumb I/O device for 2MHz 64kB RAM computer, but it works, so what :)

The documentation on github is really good - datasheets for each IC, handbook explaining CPU, electrical schema as PDF as well as Eagle files ... everything you need to lear and having fun with it :)

Also there will be soon book about building such computers from the same author (Martin Maly), at least in Czech language (not sure, if english version would be written too) - and if I understand it well, then other compatible devices are planned to be released later - I am looking forward it (even if I plan to make my own in meantime to have something more versatile - I will probably start with Arduino powered keyboard/display/I2C general bus mapped somewhere into address space)
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So sumary:
Nice, easy to build, works from first moment, much fun, lot of power and a lot of education - I heartfully recomend that :)