It's all about the data. I tried a Holland outfit called Droam (http://www.droam.nl/en/) .
For 65 euros ($110), we had 1GB of data for the month. You get a small gizmo that slips easily into your pocket. Up to 5 devices can connect to the Droam using wifi.
Once we got our hands on it (Fedex are not only bad in NZ), I used the Speed Test app, and got 250 kB down, and 80 up. But it was variable. Not surprisingly, half time in the France-Bosnia Euro 2012 qualifier in a full Stade de France, the connection dropped to non-existent.
By the way, I saw on the Metro 2 Android phones, 4 Blackberries and 1.4 million iPhones (well it seemed like that).
Using Google Navigate (we avoided: "it says we should be walking past Notre Dame, ahh there it was") and the RATP Metro app were invaluable. Actually the Metro app was perfect on the iPhone but crashed quite regularly on the Android - the reason is in the above paragraph I guess.
What was also useful was the Timeout Paris app (for the iPhone) - it used GPS and that blue dot was great.
To make phone calls when out of the apartment, we used Skype - cost a penny a minute to call a land line, (inc NZ), and about 50 cents a minute to call a cell phone. In the apartment just used Google Talk - cost of 0 cents.
So a GB of data meant we didn't have to be concerned about usage - using roaming with a NZ telco would be $10 000 for a GB, so this was a good solution.
Taking the Galaxy Tab was fine - so much better than lugging a laptop. We have had it now for a couple of months and it's impressive.
Finally a few observations about Paris
the baguettes are perfection (La Tradition) - NZ supermarket bread is a travesty (at least it was - it's years since we bought any).
when crossing the road, look both ways - they drive on the wrong side.
they use UHT milk (uggh) in the coffee - our NZ latte is called a cafe crema. I solved this by finding in a supermarket called Carrefours real milk, Lavazza coffee, and used the stovetop in the apartment.
cyclists and cycles - all ages, elegant and stylish. No revolting plastic crap helmet, lycra, hi-viz or clunky ten-speed for the Parisian or Parisienne.
in the Pantheon, there is a re-enactment of Foucault's pendulum 1851 experiment http://en.wikipedia.org/wiki/Foucault_pendulum - that was great.
when walking on the pavement - they walk on the wrong side.
I couldn't find a sensible place to post this so here goes.