Seksmisja is a classic but I think u really need to know the nuances of Polish humour. I much prefer British humour, it's different for sure. I'm glad that many Poles like Monty Python.
Seksmisja isn't a hilarious comedy, but it is definitely fun to watch.
If I were to recommend someone a quality polish humor, than I would have to go with Koterskis "Dzień Świra". It's not a typical comedy, but certainly a great one. For a more lighter note I would recommend Kabaret Potem or Moralnego Niepokoju. Just keep awal from Koń Polski, Rak, Elita, Jurki, Pod Wyrwigroszem or that Ani mru mru nonsense.... :/