These are 100 percent crops from our test scene. Despite a resolution bump from 14 to 18 megapixels, the ZS30's photo quality isn't appreciably better than the ZS20's. Viewed at full size on screen, there is visible noise/artifacts even at its lowest ISO setting. Details start to soften at ISO 200 and at ISO 400, color noise becomes more noticeable, too. At ISO 800, you'll start to see faint yellow blotching, which becomes more pronounced at ISO sensitivities above that.
Aside from the blotching and increased softness, though, color and detail are good and, for the most part, these things aren't visible at smaller sizes. Basically, if you're looking for digital SLR quality, you're not going to find it. If you're looking for good photos for prints up to 8x10 inches and Web use, and don't typically do a lot of enlarging or heavy cropping, you should be pretty pleased with the results.
Also, shooting with the camera's Handheld Night Shot mode with still subjects will improve your results. The mode takes several shots and combines them into one shot, reducing noise and improving blur from hand shake. Even if it needs to use a higher ISO, you'll get much better photo quality.