It is difficult to get English language books that describe the GDR in a sympathetic light. Below are a number of scanned PDF's which describe the struggles and succsesses of the GDR.
1) "The Triumph of Evil: The Reality of the USA's Cold War Victory" Austin Murphy. Perhaps the best, contemporary overview and assesment of the GDR, and rebuttal to the dominant narrative and caricature of the 'evil' 'East Germany'.