It's interesting in that a lot of what it does sounds like how a serge works - with the lower arm with the hole in it for the thread and how it loops and intertwines with the upper thread.
I have one machine that I'm nostalgic about, and sort of miss it - however it really did not fit my collection and I only bought it because it was neat and cheap! That one is the Davis low arm. Not that I'd want it back, but it was just such a neat machine!