The A550 is heavier and bulkier than its lower-end brethren are--though it's lighter than the competition are--but oddly doesn't make as good use of space and is less streamlined for shooting. Like many dSLRs that have to remain backwardly compatible with older lenses, the A550 has a Manual/autofocus switch on the body that you confusingly have to remember to match with the switch on the lens.
On the lower-end models, Sony puts controls for the ISO sensitivity and drive modes on the navigation switch on the back of the camera. I think that placement works better than the three, hard-to-differentiate buttons on the top of this one. It's also annoying that in a camera of this class that you have to set the ISO sensitivity via the back display--it doesn't appear in the viewfinder. Usually on dSLRs with buttons on the top right, they're placed forward enough to easily and comfortably reach with your forefinger. On the A550, they're set closer to the camera back where you can't comfortably reach them with either your thumb or forefinger unless you lower the camera.
Note how the LCD, when tucked in, extends beyond the viewfinder eyecup. That makes it relatively uncomfortable when trying to use the viewfinder. On the upside, the A550's grip is much better than that of its lower-end siblings; theirs are about 3/4 height, which feels much less secure.
Compared with the standard display (bottom), the graphic display (top) is intended to provide an educational view of the relationship between shutter speed and aperture, as well as the effect each has on stopping action and depth of field. I think it's odd that the graphic display drops the metering mode info, however. It's also a bit frustrating that Sony, which pioneered the interactive display in the A700 (where hitting a button would let you navigate the bottom view and change settings), opts for the disruptive Fn-button-into-different-interface approach (see next slide).
While I prefer the interactive displays that are becoming more common--there's less of a jarring transition between looking at the settings and adjusting them--Sony's traditional approach may seem less cramped for some shooters.