The only things that kept me watching to the end were the anticipation of some improvement in the plot (didn't happen), and the realistic settings. I wondered where they were able to film what seemed to be 1930's era buildings and streets; I see now it was made in East Germany before 1982. Probably wasn't hard to find places that hadn't changed much since the 30s.
I usually like movies that are subtle or ambiguous, or both, but this one carried those characteristics so far I was longing for a chase, a shootout, some sex, anything.
Hitchcock or somebody said films are life without the boring bits. This movie was life without the exciting bits.