I really need to sleep so I'll just list a few details that I liked. Prisoners can attempt to sneak knives out of the kitchen (apparently more likely with Prison Industry), you can call in the emergency services, I saw a guy get beaten to a pulp in the showers about 10 mins into the sandbox, each prisoner has an individually weighted hierarchy of needs, it gets dark and harder for your guards to spot prisoners at night, your guards carry torches, furniture is placed individually and certain rooms/features need access to electricity and/or water, a prisoner flew into a rage and smashed up my generator, the kitchen burned down along with a load of rioting prisoners, you can set the schedules to whatever you want, prisoners can try and dig their way out, rooms get filthy if not cleaned often enough, the electric chair takes up a hell of a lot of electricity, you can zoom in and out an awful lot.
As far as heart goes, the campaign (at least up to the second mission) seem to relay the stories of individual prisoners through a series of pretty darn sweet vignettes. It never got preachy or tried to push one particular viewpoint on you (although a variety are shown through different characters). It helps to make them seem a little more human, which is always nice. One little touch that I absolutely adored is that the music, sound effects and UI gradually change to reflect the 'vibe' of the prison. Clicks become slams and colour drains away when things start turning sour.
This was about 2-3 months back. The first two missions were finished and the sandbox mode sure seemed fully playable to me. I'd have happily paid £15-20 to take a copy home with me there and then.