It doesn't really compare in that the apple watch is a much more powerful device. I think of pinetime more as a fitness tracker sort of thing than a smart watch.
It's cute, doesn't do too many things, lasts about a week on a charge, uses regular 20mm watch bands (though has recessed lugs so can still be tricky) etc.
I use mine a lot for it's built in metronome to help me time static stretches.