Overall, the A77 delivers a solid noise profile for its class. On JPEGs, you can see just a hair of degradation on edges at ISO 800, but casually noticeable noise-suppression artifacts don't kick in until ISO 1600. JPEG artifacts are another story (see next slide).
You can see how the combination of noise suppression and sharpening both mushes up and emphasizes detail on Grace's fur and eye, producing a slightly special-effect-type look.
(1/100 sec, f2.8, ISO 800, AWB, pattern metering, 16-50mm lens at 35mm)
Without any noise reduction applied (in Adobe Camera Raw), this is what the two cameras produce. I think the size of the "grain" is what determines the type of noise-reduction artifacts you'll see. When processed, however, the images look extremely close.
For the most part, the camera does a good job of sharpening JPEGs without going overboard, at least at the default settings. The lens is nicely sharp as well.
(1/160 sec, f5.6, ISO 200, AWB, pattern metering, 16-50mm lens at 50mm)
Just a few examples of the A77's color rendering. Some were shot using the default Standard Creative Style setting--the two shots of roses on the left and bottom right tuber--and the others using the Neutral option.
I really like the new 16-50mm lens; in addition to being able to be bright, fast, and able to focus fairly closely, it produces lovely out-of-focus highlights.
(1/80 sec, f2.8, ISO 100, AWB, spot metering, 16-50mm lens at 26mm)