I spent a couple of hours, on a Sunday afternoon, at the Oskar Schindler factory. I booked my ticket beforehand, from the get your guide app. I collected my ticket from the guide at the arranged time, which meant not having to queue (heavy rain, no shelter if you don't pre-book). I would also advise you get the audio guide.
The tour itself covers both the German and Soviet occupation, as well as covering Schindler's time. It was very informative, with interactive displays, etc.