The iPad will be available in WiFi and the more expensive 3G version. Nick Bilton of NYT says that if you are planning to your iPad for home / personal use, there’s little point in spending that extra 130 bucks for the 3G version.
If you plan to use your iPad principally at home, getting the Wi-Fi version is a no-brainer. With a stable, constant source of Internet connectivity, you can use all of the iPad’s features as much as you want without the additional cost of 3G. When you don’t have a connection, you’ll still be able to use some embedded applications like e-mail, photos, video, contacts, calendar and the iBook reader in offline mode.
If you plan to use the iPad as a laptop replacement, you might want to go with 32 GB or 64 GB to ensure enough storage for music, photos and movies. But if you’re only going to surf the Net, watch the odd movie while traveling and read e-books, the 16 GB model will suffice. link.
The downside is that an iPad has no USB ports so any data transfer has to happen over the Wi-Fi network. The iPad Wi-Fi model won’t have GPS capabilities so any location aware apps won’t work on that model.