Thankfully, Poland has been providing tens of thousands of books, magazines and documents online in both Polish and German over the past five years or so, and the collections are growing fast.
And let me guess, most of the authors of those books have some connections to Gazeta Wyborcza, like Gros?
showing both negative AND positive aspects of the Prussian, Austrian (and occasionally Russian) times
Is that for real, or are you joking? The only positive aspect of partitions was that the people of Wielkopolska united against germanization. Negative aspects were that our language and culture were being slowly killed in non-polish schools, german quasi-banks were claiming polish land and austrian administration closed over 89% of polish-owned mines and production companies. Read "Polskie logos a ethos" by professor Feliks Koneczny for nice statistical compilations of damages and hardships that Poland and Poles had to suffer under partitions. The same author is also listing out all the flaws of polish ideology and political thinking of those times, so you can't claim he isn't objective. More so, prof. Koneczny lived under partitions and later in II Rzeczpospolita, so he has a better overview of the situation than today's historians.