While a slicker, more polished interface will do wonders, I do suspect that a lot of the returns right now are still network effect issues: People who get the Tab as a present and then wonder why they can't run all those cool apps that their iPad toting friends have, etc. I would expect that return rates are much higher than iPhone return rates on smartphones as well, for the same reason.
That is changing, of course. The app situation -- and the network inclusion -- is quickly improving.
The Tab only makes sense as a device significantly discounted below the iPad. That it is actually the more expensive option is just perverse.