It's one of the first things you learn once you start getting 'serious' about digital photography: you can almost always get better results by shooting in raw mode than relying on your camera's JPEG engine. raw files have a greater scope for post-capture adjustment, in terms of color, brightness/exposure and detail extraction. The downside is that getting the most out of a raw file takes time. Sometimes it is worth it, sometimes not so much.
The A77 is one of those cameras where it is definitely worth it. The A77's default JPEG rendering delivers smooth, colorful images which will satisfy most people most of the time, but to see anything like the camera's true potential you really should switch to raw mode. All of the raw files on this page were processed 'to taste' in Adobe Camera RAW using a combination of sharpness and noise reduction settings intended to get the best from the A77's files in terms of color, sharpness and noise.
In some situations, the difference in terms of sharpness and detail between a default JPEG capture and a carefully-processed raw file is profound, as you can see from the ISO 100 scene, below.
ISO 100 JPEG
ISO 100 Processed raw
The same applies to the A77's high ISO output. At medium to high ISO sensitivity settings you're not only fighting against the camera's slightly soft default JPEG output, but also against the softening effects of noise reduction. By shooting in raw mode, you can take control over both sharpening and noise-reduction, and with a little care and attention you can draw a lot more detail out of your scene.
This image was shot in poor light at ISO 2000, and you can see how much detail the A77's noise-reduction system has removed from the fine bubbles in the beer in this glass. By adjusting the sharpening and noise reduction in Adobe Camera raw I was able to recover a significant amount of extra detail, albeit at the inevitable expense of some additional 'grittiness' in areas of plain tone.
ISO 2000 JPEG
ISO 2000, Processed raw
This next shot is a pretty extreme example, and one where to be fair, you might prefer to stick with the A77's JPEG rendering if the image isn't meant to be viewed critically.
Shot at ISO 6400 in very poor light, the A77 has given a characteristically muddy exposure in this sort of environment. The JPEG file is acceptable, and - thanks to noise-reduction - impressively smooth, but it is low on detail and needs a 'boost'. In Adobe Camera raw I brightened the image by +0.5EV, fine-tuned the white balance and increased the saturation of yellows and reds. I also experimented with the available noise-reduction settings, increasing color noise reduction as far as I dared before losing color saturation, and luminance noise reduction just high enough to take the edge off the 'grit'.
ISO 6400 JPEG
ISO 6400, Processed raw
The final image is brighter and punchier than the original, and contains more detail but - naturally - also more noise. This shot would probably be too noisy to risk a large print, but the improvements made to the raw file are very obvious at moderate magnifications.