I like Nexus One. I am, however, missing some features I use heavily on my iPhone.

Skype - the version of Skype I found for Android does not work as I am used to, that is it says, it will cost me money.

SIP - On my iPhone I use SIP. I installed a couple of apps from the Market but neither works, saying that no suitable data network is available.

Finally, on my iPhone I have an application called Unrestrictor, which allows me to use the GSM network as if it were a WIFI. Perhaps this is not needed on android (?)