Who wants to Upgrade to the Z30?
You get a bigger screen, but a lower resolution. The Z30 is at 1280 by 720 where the Z10 was 1280 by 768
The Z30 will be a bit faster due to the processor and will have better battery life because of the bigger battery.
So its up to you to see if its worth paying for another $600-700 device for slightly better/different specs and a different size of phone