Continuity of consciousness, and it's important because without it, the me that results from the uploading isn't this me, just an instance of me, which are not the same thing. The fact that there is a copy of me going around does not change the fact that this instance of me is dead.
Whenever you enter deep sleep you lose continuity of consciousness. Whence your intuition that continuity is important? Are you not impressed by timeless physics, nor Tegmark's multiverses? In a spatially infinite universe with particles being indistinguishable and whole Hubble volumes also being indistinguishable (the standard cosmological position), in what sense are different 'you's actually different people, even if there is no causal connection between them?
...The fact that there is a copy of me going around does not change the fact that this instance
Giulio Prisco made a blog post giving permission to use the data in his Gmail account to reconstruct an uploaded copy of him.
Ben Goertzel copied the post and gave the same permission on his own blog. I made some substantial changes, such as adding a caveat to exclude the possibility of torture worlds (unlikely I know, but can't hurt), and likewise gave permission in my blog. Anders Sandberg comments on the thing.