Interestingly, the screen always shows you the strength of the 3G network around you, even if you haven't signed up for an AT&T plan. You just can't connect until you sign up.
Do You Really Need 3G?
Although the debate until now has been whether to go 3G or not, iPad buyers actually have another option: Buy the less-expensive Wi-Fi model and get a Verizon or Sprint MiFi device. MiFi units are pocket-size mobile hot spots that convert cellular data signals into a small Wi-Fi bubble -- good for allowing up to five separate Wi-Fi-enabled devices to connect.
MiFi units from Verizon sell for $269.99 retail (or $49 with a two-year contract, including instant discount). Monthly data plans cost $39.99 for 250MB or $59.99 for 5GB. Sprint charges $299.99 for its MiFi unit, but instant savings and a $50 mail-in rebate bring the price down to zero -- if you buy a two-year contract. Sprint has two separate monthly connection plans, and both cap 3G use at 5GB of data. One plan offers unlimited 4G service (which isn't widely available) in addition to the 5GB-capped 3G service; both plans cost $59.99 a month.
One benefit of using a MiFi device over the built-in 3G is that, as far as the iPad is concerned, it's connecting to the Internet via Wi-Fi. This is important because of the limits to what can be done with 3G connectivity. For instance, App Store downloads are limited to 20MB, so forget about downloading that large game or that must-have software (such as the popular chemistry app, The Elements) while you're away from a Wi-Fi network.
For now, Skype and ABC's video player won't work at all with 3G (although an updated ABC app is reportedly on the way); YouTube and the Netflix player down-sample their video streams. This won't happen if your iPad is connected to a Wi-Fi network -- or to a MiFi unit.
I should note that while MiFi might be less expensive at first, the monthly charges do cost more over time than going with the iPad 3G and AT&T's network. MiFi makes sense if you want to offer access to more than one device or if you really need high-quality streaming video on the go.
If location-based services and GPS are important to you, the iPad 3G delivers. I've found that the GPS is more accurate on the iPad than it is on the iPhone. (iFixit's teardown of the newest iPad exposes a Broadcom BCM4750UBG Single-chip AGPS Solution; iPhone 3GS uses an Infineon Hammerhead II.) And it's more reliable than the Wi-Fi model, which offers similar GPS functions but can't pinpoint your location as well.
But that's of little consolation to those who want 3G access for specific tasks that the iPad 3G just can't handle, such as streaming episodes of Lost from ABC's video player while on the road. While it's nice to have a continuous Internet connection -- as well as true GPS capability -- I have to reiterate that unless you specifically need GPS, the less-expensive iPad, coupled with a MiFi device from another provider, might be a more logical solution.
One way in which the 3G model might be a smarter buy than the Wi-Fi-only unit is if you want to use the Find My iPad feature with a MobileMe subscription (a $99 yearly Internet service suite from Apple).
Find My iPad allows you to log onto Apple's MobileMe site and track down the location of a lost or stolen iPad. While this feature is available on the original iPad, if you've enabled passcode protection there's no way for the iPad to log into a wireless access point -- unless the finder/thief frequents the hot spots that you've already used.