The A100 had Eye-Start Autofocus, which initiated focusing when a sensor detected an object--ideally, your eye--behind the viewfinder. In the A700, Sony augments it with a grip sensor to minimize false starts. I still ended up turning the feature off: it doesn't seem to buy enough focusing speed to ameliorate the constant hum of the lens in motion.
Yes, it's got HDMI output for displaying your photos on an HDTV, but more notably the A700 adds dust- and weather-resistant seals to all the covers. The body itself is composed of a magnesium output shell over an aluminum chassis, and it feels solidly built but not overly heavy, even with the new battery grip.
Though there are plenty of direct controls, you can access almost every setting from the Quick Navigation display on the LCD. Sony has nicely beefed up its in-camera Creative Style settings (2), giving you the ability to start with a preset (1) and change the individual parameters to suit your taste. Additionally, a new Advanced Dynamic Range Optimizer setting (3) lets you tweak the DRO settings and save three custom versions.
The joystick is a great improvement over the navigation control used by the A100. It seems to be the same size as that of the 40D's, but it extends farther from the body and has a bigger surround, so it's more comfortable to use.
Like Nikon and Pentax, Sony provides a switch for choosing among single-AF, continuous-AF, automatic-AF, and manual focus. (In contrast, on a Canon dSLR you select among the options electronically.) However, I'm not fond of the design of the switch on the A700; I find it awkward to manipulate.
The buttons on top feel identical, but they're big and broadly spaced, with large labels that make them easy to distinguish when you're rushing. The mode dial, too, is big and easy to control.
You can assign three custom groups of settings to the MR (memory recall) slot on the dial, which is nice, but the way it operates gets annoying. If you're in setting 1, for example, to switch to setting 2 you must rotate the dial out of MR and back to bring up the screen, which will allow you to select it.
The optional new vertical grip, which holds two batteries, has the exact same feel as the horizontal grip; for instance, it preserves the relative position of the viewfinder to your hands, and replicates all of the controls, including the joystick and custom function button. In fact, I frequently forgot I was shooting vertically and tried to manipulate the AF dial below the lens, which (for obvious reasons) wasn't there.
Though they're not easy to differentiate by feel, the A700 uses big, clearly labeled buttons with decent tactile feedback. You can assign a single custom setting for the C button--such as pulling up the image size choices--many of which already have direct controls. It defaults to accessing the Create Style setup screen, which seems a bit odd--it's not something you generally need quick access to while shooting.