Some of the possible benefits to mind uploading would be: the ability to completely modify your surroundings (thus experiencing things essentially first-hand that would be utterly impossible otherwise); the ability to escape the dangers of biological life (there could easily be tremendous safeguards against 'hacking' or any such); the ability to effectively compress time by modifying your own clock speed (thus making minutes seem like days if you had the computing power/speed); and access to assorted other amazing ways in which you could alter or improve your experiences.

However, a problem I've found with the idea of mind uploading, or of most other forms of ego transfer (such as Other Memory and gholas from the Dune series), is the lack of continuity.

That is to say, it's hypothetically very possible to emulate the functions of the human brain so perfectly that some exact copy of a person's thought processes (memories, emotions, etcetera) could be created perfectly. And that copy would, in effect, be the person who it was modelled on. But the person would not be the copy--she would still feel exactly the same, except she'd be aware of (and able to interact with) a digital version of herself.

Which is really an interesting idea, and all, but it doesn't effectively provide anything more than a very abstract form of immortality. The biological human would still grow old and die; would not have access to all the amazing capabilities of her digital self; would effectively gain very little concrete benefit from it aside from the simple knowledge that someone exactly like her was being given an amazing experience.

Of course, this isn't an insurmountable obstacle. Given the level of technology necessarily involved, for instance, it wouldn't be too difficult to imagine simply implementing some form of MMI (or BMI, pick your acronym), and then moving the still-active thought processes from the brain to the computer, such that continuity is maintained and the digital version of the person is, in reality, the same consciousness as the biological person. Or a subject could gradually have her entire brain replaced with cybernetic implants that maintained the exact function and state of their biological counterparts (to avoid memory or identity loss) and then once her brain was entirely digital, transfer her consciousness into a computer system that way. Of course, whether or not a consciousness could remain the same during such a transfer is rather unclear.

But then, this is all hypothetical anyway.