The Canon Powershot S110 brings some key performance improvements as well as the touchscreen which makes this 4th generation S series camera probably the best yet.
The photo quality from this camera is impressive considering its sensor size. If I was to be really nit-picky I would say that the sharpening in the JPEGs appears a little crude at times and the colors aren't as punchy or contrasty by default as they were in the S100. But color performance is still pretty good (I like the colors better than the ones from the Sony RX100), detail capture is very good, and ISO performance is excellent. At ISO 800 the camera does a very nice job balancing out detail retention and noise reduction and even ISO1600 photos look good as long as you're not blowing them up to huge sizes. Shooting RAW will help you wring out even more detail. Dynamic range is also quite good. The camera tends to overexpose in bright conditions and blow out highlights. Which is pretty typical for this class of camera. Taking everything into account though, I would say the S110 probably has the best overall image quality of any of the S-series cameras so far.
Canon uses the same 5x F2-F5.9 lens as they did in the S100. It's unfortunate they haven't taken the opportunity to put a faster lens in this model because most of the competitors have much faster lenses on their cameras. That said, the lens is fairly sharp. It also zooms in and out fairly quickly.
Sadly, the camera has lost the little indent on the front which helped give you a more secure grip. However, the surfaced is textured in such a way where you can still get a decent grip, and it's not slippery like the Sony RX100. The LCD screen is 460k dots, and while it's pretty decent, I think Canon should have taken the opportunity to upgrade the resolution with this model. The big update this year with the LCD is that it is now a touch screen. To be honest, it's not very practical for adjusting camera settings but does work extremely well for touch focus and touch shutter. It's a much better setup than having to go into the menu to adjust the focus area. The touchscreen overall, though, is very responsive and works well.
The control ring up front remains on this model and is still excellent to use. With decisive clicks everytime you adjust something. You can of course customize the control ring up front to adjust a number of settings.
As far as performance goes, shot to shot times are about the same as the S100 but autofocus performance has improved on this model. I wouldn't say the camera has blazing fast autofocus but it should be plenty quick enough in most shooting situations.
As for the video, it is surprisingly good for such a small camera but is most suitable for short clips.
This model has since been replaced by the newer S120. The S120 is a faster camera overall and has better video capabilities. Plus it has a slightly faster lens but still F5.7 on the telephoto end. I have also heard some say that the S120 is worse at high ISO but it appears about the same to me. If you're a still shooter who doesn't dabble into serious video shooting or need the extra burst performance, you can get the same photo quality and still respectable performance from the S110 at a much cheaper price.