In terms of build quality and design, the A300 is, not too surprisingly, pretty much identical to the A200 and A350. The body is made of plastic, and while it is well made with good fit and finish, it has to be said that in places it feels like it could be a bit stronger. It's not going to fall to bits in your hand, but I wouldn't want to drop it. Then again, there aren't many DSLRs that I would want to drop. The A300 is larger and heavier than average for an entry-level DSLR, but it is by no means bulky. It measures 130.8 x 98.5 x 74.7mm and 582g body only, not including battery or card. For comparison the Nikon D60 weighs 495g and the Pentax K-m weighs 525g.
The body design is derived from the Minolta Dynax 5D by way of the Alpha A100, and is very pleasant to handle. The big rubberised handgrip is comfortable and secure. The controls are mostly sensibly positioned, although the row of four buttons on the left of the monitor are a little hard to access due to the raised edge of the monitor.
The A300 is aimed at much the same entry-level market as the A200. It has a relatively simple control interface, with a large main mode dial on the left of the top panel that carries the usual exposure modes (program auto, aperture and shutter priority, and manual) as well as full auto and six commonly-used scene modes. Most of the frequently-used options have their own buttons, including ISO setting, self-timer/drive mode, exposure compensation and exposure lock. Adjustments to exposure settings are made using a control wheel located just in front of the shutter button. A Function button on the back accesses a brief menu with six adjustable shooting parameters, including flash mode, metering mode, autofocus mode, autofocus area, white balance and the D-Range Optimiser (which boosts shadow detail in high-contrast shots). Other options are relegated to the main menu, including the Creative Style option, which provides a range of contrast, saturation and sharpness control.
Sony's live view mode differs from that offered by most other manufacturers in that the full nine-point phase-detection AF system (with cross-type centre spot) is available while using the monitor. This is much faster and more accurate than the contrast-detection live view AF systems used by Canon and Olympus. The same wide-area, centre zone or selectable AF point modes are available in both live view and viewfinder modes. The autofocus system is the same as the A350, and is fast and accurate, with good low light performance.
On the subject of the viewfinder, it's hard to say definitively without having an A200 or A350 side-by-side for comparison, but it seems to me that the A300's viewfinder is slightly smaller with lower magnification than either of its siblings, giving it a rather tunnel-like appearance.