About the "WiFi is good enough when high speed is needed" part

Yes WiFi is great when you need high speed.

But I don't know if there is free WiFi all over the place where you live, work, move around.

But here in Denmark EU, and the parts of EU I have been in.
There is not free WiFi acces.

There is not even full covert of payed WiFi.

So many times is easyer just to have you own high speed internet connection whit you.

An by the way the WiFi hotspots that we have over here.
Beside you have to pay to use them, then if you are lucky then its 2Mbit/s down 512Kbit/s up.
And that you have to share whit all that is om.

Whit 3G you get around 700Kbit/s down almost anywhere.
3.5Mbit/s need most citys, and 7.2Mbit/s in the big citys, and you don't have to share the speed whit anyone else
and the up speed is 384Kbit/s

So that is why I like 3G better then the WiFi part.

But ok if you only use you phone at home, at you own WiFi spot, and at work/school, where you have permission to log on to the WiFi network, then yes, the WiFi is cheaper and faster then 3G