Maybe because the 2nd ballade was dedicated to Schumann (who told Chopin that he considered the 1st ballade to be his best work, which pleased Chopin who thought the same), I now hear a Germanic dance melody in the opening theme, not Irish-sounding. As other people have pointed out, the opening theme is supposed to represent a tranquil lake. When I first heard the piece, not knowing anything about the poem about which it is purportedly based on, I didn't see a lake at all. The music seemed to have a wintry feel to it, as of a little town sleeping under a comfortable light snow. All is peace and quiet until a storm arrives and billow of wintry air roars through.
The first time I played the piece, I forgot about the presto that procedes the quiet opening theme. After turning the page, my mouth gaped open when I realized what was in store. "Jumping on a fire truck" is about it. I actually laughed, shut the music book, and put off practicing for another time. If you don't use the correct fingering on the right hand (using the fourth and fifth fingers for the top-most notes), you can't possibly get it right. And then there is the difficulty of the last page, where you need to be so careful with the right hand, while all the time keeping the momentum of the piece from screeching to a dead halt. And why play the last few bars, where the principal theme returns, if you haven't played well what just preceded it? It's like a figure skater falling on his triple jump, then trying to finish off with a smile. No need to bother.