Wow, it is the first time I have heard that song with Vocaloid. Very impressive.

I have played around quite a bit with Vocaloid (not v5 though) and I'm quite sure that you can get good results if you have A LOT of patience and time to program it.

It is - however - worth considering if you are not better off paying a real singer a small amount of money to do the vocals - if you check places like fiverr.com and others, you will see that it is not too expensive to get a real singer.

I guess it is a matter about how your value your time... you can for sure get good results with Vocaloid (or Realivox Ladies, etc.), but if you spend 3 days to make it sound good it might be worth considering other options.

Just my 2 cents.
Will