The module in general is OK, it does it's job as advertised.
- make absolutely sure that the connected AC supply, when rectified and filtered provides at least 12V DC, otherwise the relays won't click. I've used a 9V AC transformer, and it was not sufficient.
- I had changed the filtering capacitor to a 25V unit. The provided 16V cap was very much on the edge from my point of view, and it would not live for very much long time, if run at the limit.