I thought it was brilliant.
The weakest episode was, I thought, the last one, where both the protagonists learn about their personal histories - it felt like an anticlimax.
This business of shameful secrets is the whole story (emphasised by the sinister Frenchman and the threat of exposure) but in the end, I didn't think Arthur's secret was so terrible - or perhaps, didn't merit the depth of the buildup.
But the journey through the production was worth it!