Listening to this as I type and it's damn good! As ep1str0phy writes above, the music is extremely directed: it goes wham-bam right through the middle with lots of drive and energy.
The liner notes mention that the Joachim Kühn Trio + Rolf had been touring and playing larger venues in the GDR (because Rolf was such a famous guy, remember he won the Downbeat award in 1962). Joachim considers this music the best his trio + Rolf have played during that period. When he left through Austria, he took a copy of the tapes along and sent it to Nesuhi Ertegun who really liked it and wanted to release it on Atlantic. They then played the Newport Festival in 1967, however, where Thiele offered to record them for Impulse!, which resulted in the "Impressions of New York" album. Ertegun considered two albums to be too much for the market and the Atlantic project was canned.
Rolf is a strong player who has no problems keeping up with the exuberant ideas of his brother and Koch, the bassist. Technically, Schwartz may not be the best drummer, but he is very free and very supportive. Seems he has some big ears and lots of experience playing with this group.