The iPad now has all the technical bits in place to become the household computing center for most people.
As an iPad owner myself, I have to emphatically disagree. If people are satisfied by the computing experience offered by the iPad, their expectations are way too low.
It has built in e-mail, web
It's simply not good at browsing the web. It's slow, it's full of ads, it crashes so goddamn much (responding to the Slashdot poll crashes mine about 2 out of 3 times). Compared to a laptop, or certainly a desktop, it's a terrible browsing experience.
video consumption, photo and video management, music
It does video alright, but lots of web video outside of youtube just won't load properly half the time. It's difficult to control playback (pause isn't quick enough, seek bar is clumsy and inaccurate). And unless you plug in headphones, music or any video relying on sound will be greatly degraded.
Yeah... *basic* document creation. Touch keyboards just aren't good enough to type anything substantial, and let's not even get into the ergonomics of extended typing on it. It doesn't have the processing power to create music, and I wouldn't try any serious image creation on it.
Some of these problems will get better, I assume one day they'll make one with enough horsepower that I can vote in the damn slashdot poll. But tablets are toys, they aren't real computers and they don't replace real computers for most of the applications you mentioned.