Streaming video over 3G is low-resolution and blocky, and the ABC Player won't operate on 3G at all, according to early reviewers.
Cult of Mac's Leander Kahney delivers the verdict on iPad 3G streaming video in plain English:
The honeymoon is over. Ive discovered my first major disappointment with the iPad 3G, and Ive only just started playing with it. Video over 3G on the iPad totally and utterly sucks.
The picture is noticeably downgraded on a 3G connection. The built-in YouTube app delivers video thats very low-res compared to the video it delivers on a Wi-Fi connection. Its barely watchable.
Kahney provides screenshots illustrating the difference in video quality over 3G vs. Wi-Fi. He notes that the difference has always existed on the iPhone, it's just more noticeable on the iPad.
Netflix and YouTube work in 3G in low-resolution, but the ABC Player still requires Wi-Fi, according to Alexander Vaughn writing at AppAdvice. Apple requires developers with streaming video apps to write them so they adapt to different networks. Netflix and YouTube wrote their apps according to the specifications, ABC didn't.
Developers are required to write video apps for the 3G device using HTTP Live Streaming technology, and deliver a stream of 64 Kbps or less when network conditions demand low bandwidth, AppAdvice says.
Problems with iPad video over 3G are a real shame, because video is otherwise gorgeous on the iPad, whether stored on the device or streamed on Wi-Fi. Since I got the device a month ago, I've watched hours of video podcasts, and some TV and movies, using the Netflix and ABC Player apps. I even watched a movie on the Netflix app streaming over Wi-Fi on a night-time Delta airline flight from Des Moines to San Diego, it was fantastic.
3G Monthly Cost
Apple blogs also have details on the financial rates for 3G. I've been very impressed so far by the consumer friendliness of 3G service for the iPad; you're not required to sign a long-term contract, you can buy month-to-month.
The two plans available are a low-usage plan offering up to 250 MB of combined incoming and outgoing data for $14.99 for 30 days, and $29.99 for unlimited, unmetered data for the same period.
One element that's not so consumer-friendly is the 250-MB limit. Do you know how long it takes you to use 250 MB of Internet bandwidth? I sure don't. Without that knowledge, how are you supposed to make an informed decision whether to spring for the 250 MB plan or the unlimited plan?
The good news is you don't need to worry about it. The iPad gives you the option of starting with the 250-MB plan, and then it lets you know when you've gone through the limit and gives you the option of upgrading to the unlimited plan, according to Glenn Fleishman at TidBits, who has a detailed write-up of the service plans.
How long does it take to go through 250 MB of data on 3G? About an hour of streaming video, Fleishman says.
Potentially bad news on the 3G plans: They automatically renew every month, unless you remember to cancel them. Some people are gong to get dinged for monthly charges when they intend to cancel but forget.
The iPad may finally drive me to jailbreak my iPhone. I haven't bothered to jailbreak the device until now because I just haven't seen the point, however, the MyWi app will turn your iPhone into a Wi-Fi hotspot, so you can use your 3G-less iPad while out and about. Spirit software makes jailbreaking your iPhone or iPad easy, says Sayam Aggarwal at Cult of Mac.
More about the iPad:
Update: The ABC Player app has now been updated to support 3G.