The biggest two changes are the six_awesome_new reading fontsand the distraction-free, full-screen reading interface.
I just updated Instapaper for my iPad and iPhone. For free. Marco puts a lot of thought and care into this application and it only costs a few dollars. If you'd like to mark things to read later I suggest grabbing Instapaper.
Side note: I'm hoping to integrate the brand-new-not-even-finished-yetNilai with Instapaper in a future update. I do not foresee Nilai supporting any other read later services.