There's little doubt that the next iPad will have a more powerful next-generation processor with improved graphical capabilities. Despite the power boost, that chip, which most people expect to be called the A6 (the iPad 2 and iPhone 4S have the A5), is supposed to be more energy-efficient, so it isn't expected to be a battery killer.
Whether the A6 will be a quad-core chip remains unclear, but we should get all the details in March, with Apple boasting of, say, "4x faster graphics than iPad 2."
Improved battery life
While the iPad 3 is expected to have a higher-resolution display that would be more taxing on the battery, Apple's (presumed) A6 processor may be more energy-efficient.
Whatever the case may be, it's likely that the iPad 3's battery life will at least match that of the iPad 2. Apple has never yet released an iPad or iPhone that had worse battery life than its predecessor.
With the bumped-up processor, the next iPad will be able to run Siri's voice recognition feature (for those who care about that feature).
The sound and speakers in the iPad 2 were an improvement over what the original iPad offered. Expect a slight sound upgrade with the iPad 3.
Will the iPad 3 be the first Apple product to support 4G networks? That's the speculation.
Of course, a 4G connection would probably mean an even higher monthly bill than the 3G data plans currently offered on iPads. And data caps as well.
Better front and back cameras
One of the weak points of the iPad 2 is its cameras. They're simply nowhere as good as the ones in the iPhone 4S (or even the iPhone 4).
There's strong speculation that both the front and back cameras will be significantly upgraded, with the back one (the one you'd take pictures with) getting the iPhone 4S' camera and the front going to HD for FaceTime HD video chats. A flash might be integrated into the rear camera as well.
Thinner, lighter design
The rumors have been all over the board on whether the iPad will be thinner, or thicker to accommodate new parts. In the past, Apple has always managed to shrink the size of its next-generation products, so it's hard to bet against it doing that yet again with the iPad 3. But the new iPad could very well get slightly bigger yet lighter at the same time (in fact, it's more important for it to lose weight than to shrink).
The screen resolution in the iPad 3 is expected to increase, from the iPad 2's 1,024x768 pixels to 2,048x1,536 pixels. That's from 786,432 pixels to 3.14 million.
Rumor has it that Sharp may be supplying the LCD panels, which will offer QXGA resolution with a pixel density of 264 ppi (300 ppi is considered a Retina Display). By comparison, the pixel density of the iPad 2's screen is 146 ppi.
That's obviously a big jump if those numbers end up being real.