Always show a full line, or nothing. You could "fade" the last line to provide a visual indicator that there's more there, but you're intentionally truncating it for readability, or some other visual indication like the "more" link, but cutting the last line of text in half is the worst of all worlds. It makes that line unreadable.

Ideally you would make it configurable for how many lines to show before truncating (or turn this off completely).