We'll see how well saves will work between major updates. Between 0.19.0 and 0.19.5 it worked pretty well and they've had some months to improve it futher. I'd fully agree that there's very likely a going to be significant chance to enounter additional bugs while using old saves, but it's still something different to claim saves don't work at all.
From what I saw, I think the loading system they implemented is very promising. They re-play all triggers for the state machines so that after loading the machines have the correct state (machine states cannot be saved directly).
I came accross a limited number of cases where this would lead to problems nevertheless. One example was the quest where Debbie sends you to Diane late at night with the cake, where you have to rescue her from her milking accident in the barn.
In version 0.19.5, this sends you directly from Debbie to Diane, without any possibility to interrupt and go somewhere else. You can only leave Diane after completion of that quest. No problem here.
In version 0.19.1, however, you had to leave Debbie, go to main city map, and then to Diane, triggering the second part of the quest. It was possible to save while in the main city map, which I did. Loading that save with 0.19.5 will lock you into any location other than Diane's because you cannot leave without completing Diane's part of the quest, which is not possible if you now go somewhere else. So, the save can be loaded quite well, but because of the changed game logic it is probably bugged.