I tried to go iWork only for a while and numbers barely made it for me. It had too small a level of functionality and in exchange was more complicated than it needed to be to get a small amount out. I found Soulver (a re-imagining of the calculator interface) was both simpler and more powerful for straightforward calculations -- by the time it tops out, Numbers has probably topped out.

But the home point is a good one: Numbers was great for making up a weekly chores sheet for the kid, easily decorated with fun photos and such. Still: does that justify Apple's investment?