The T99's photo quality is average for its class, but can be very good depending on your needs. The camera is capable of consistently nice snapshots, particularly outdoors in daylight, mostly because it produces bright and natural and fairly accurate colors up to ISO 800. Sensitivities go from ISO 80 to ISO 3,200, but usability for prints more than 8x10 inches drops off at ISO 200 due to noise. Add to that the watery effect of Sony's noise suppression and lens distortion at the sides and corners and you end up with pictures that appear soft and painterly. If you're OK with some noise in exchange for getting a shot, though, photos up to ISO 800 can be usable for small prints or for online use, as long as you're not doing a lot of cropping.
Though not exceptional, the T99 does well at ISO 800 giving you a fighting chance of getting a decent hand-held low-light photo. That is assuming you don't mind noise, softness, and a painterly look to details. However, I wouldn't count on using ISO 1,600 or its highest setting of ISO 3,200 as colors look washed out and noise results in graininess and yellow blotching. You can even see the yellow blotching in the fog of this photo.
Again, colors are pleasing and consistent from the T99 up through ISO 800, which puts its photo quality slightly above other lower-end touch-screen models. (And I mean slightly.) White balance and exposure are also good.
The T99's lens starts off very wide (top) and since it's an internal lens the zoom is limited to just 4x (bottom). It'll pull you a little closer to things, but mostly it's best suited for improving the framing of your photos. At the very least it helps counteract some of the lens distortion.
What brought the overall photo quality of the T99 down is its lens distortion. Sony keeps the barrel distortion in check for the most part. There is some asymmetrical distortion on the left side (top). There's no sign of pincushioning at the long end of the zoom, though (bottom). However, there is distortion in the corners that pulls subject up and in. The lens isn't particularly sharp either. It's OK in the center, but drops off to the sides and corners making subjects look soft and smeary.
The camera produces a fair amount of fringing in high-contrast areas of photos. For example, on the bottom of all these bulbs is purple fringing while the right sides have a nice yellow/orange fringe. For the most part, it is only distracting when photos are viewed at full size or if heavily cropped.
The quality of the Sweep Panorama photos isn't great. It's a cool feature and it should be enjoyed for what it is--an easy and fast way to shoot scenery. But they're nothing you're going to want to view too closely or print at full size.