Capabilities wise it seems to be about the same as a MOS6507 like you would find in an ATARI 2600, save for the fact that it's clocked at around 1/5 the speed of that budget priced and somewhat anemic chip. Being launched 2 years later it is not a big surprise it struggled to find a market in the US.
FTA: Back in 1975 the Faculty of Electrical Engineering of the University of Ljubljana […] began work with Iskra and AMI to develop an indigenously produced processor […] It wasn’t meant to be a general purpose computer type processor cranking out spreadsheet formula results.
No CPU of that time frame was. http://www.bricklin.com/history/saiidea.htm: “The idea for the electronic spreadsheet came to me while I was a student at the Harvard Business School, working on my MBA degree, in the spring of 1978”
https://www.righto.com/2013/09/the-z-80-has-4-bit-alu-heres-...