Hi @macius,
I come from Shotokan myself and have been training systema for about 7 years now. The focus of systema is to get control of the opponent at or before impact in such a way that you break their structure hence is easily off balanced and taken down. There is many concepts in systema that just dont exist in shotokan and karatekas of any style should try systema if they have the opportunity, because they would add stuff to their repertoar that gives them the edge in many situations.