This is just my opinion, but I don't think it is very strong or very unique.
Many
problems with this:
1. The post card is tiny, therefore not real.
2. The post card is
pre-printed with information like the room number. Not real.
3. The cards can't be shuffled
freely.
4. The routine seems procedure heavy
5. The whole thing just doesn't seem natural.
This feels like an effect where the creator was trying too hard to just come up with
something to sell.