One easy thing about Polish is that there's only one conditional
The funny thing about it is that the third conditional can still be very
rarely heard among Polish speakers. I was truly amazed to hear a rather young voice using it spontaneously and in a most natural way on the radio about half a year ago. Obviously, you won't hear the Past Perfect tense being used in the streets or in a shop, but it can occasionally be quite useful in a intellectual discussion on the radio to make the speaker sound precise and elegant. The other funny thing about it is that the old and middle-age generation (I'm not sure about the young generation) can still be sure about its grammatical forms (which are easy), though they don't seem to use them in their everyday life.
If I had won the lottery, I've have bought a new house. (but it's too late, I didn't win)
Gdybym wygrał w lotto, kupiłbym nowy dom.
Just for the curosity of some PF members - the above sentence with the use of the Polish Past Perfect tense (czas zaprzeszły):
wygrał w lotto, kupiłbym był