While I think that the diamond structure on the top is going to be absolutely stunning, especially when it is lit at night; I think there is a major problem with this tower. Most pictures I have seen of it are from the memorial side, which is its best side by far. However, when I see renders from say, the ESB, II WTC ends up looking very plain. Personally, I think buildings that have all their tricks on one side are fine, as long as they do not dominate the skyline and mostly will be viewed from that side. For example the Smurfit-Stone Building in Chicago (which II WTC has already been compared to) has the same type of interesting slant, but the boring back of the building is basically hidden. I doubt there will be anything in our lifetime to hide the back of II WTC from midtown.
In summary, I think this design might have actually been better if it was shorter and in the location of WTC IV. Then the back would have been hidden by the rest of downtown. Overall, I give it a B+.