I ported my personal number across on friday. I ordered the Skinny SIM with a new number and placed it in another device. I couldn't find the option in the portal to start a port, so I had to call up to have it done. After that, the process was pretty quick.
My main dislike right now is the app. On my 5x (running 7.0), I can't scroll up or down, only the balances can really be interacted with. On my iOS device, the quick buy is partially cut off and doesn't allow you to scroll either. Seems like it could be fixed with a little CSS. But overall the experience feels clunky with it not being a native app.
Edit: set correct android version
Could you possibly mail me some screen shots highlighting the issues you have with the app (and note the device on them as well).