While the manga isn't over yet (but it is nearing the end), I have a good feeling about the ending. Arakawa-sensei is pretty confident herself, she says. According to my sources she has pointed out she already knows how she wants the manga to end. So I have no worries.
As for the anime, I truly enjoyed the ending. Yes, I can see how some-if not many-were disappointed with it and perhaps I felt as I was left slightly unsatisfied. But it was still nicely done, and it left a good memory to the franchise.