Just received the the HF-S21 one week ago, and started to compared to the HS-S10 which I still have, The S21 is really full of new features and loaded with new workflows. These are a few of my first impressions.
PQ------Excellent, as good if not better than the S10.
Touch Screen------Very skeptical at first but found after one week of use that it was easy to get used to and down right a must in order to take advantage of all of the new features. The touch screen option is very good in implementing multiple task that previously required the joystick except that now every choice is exposed on the screen. It makes it very easy when you see the results right away. Menu navigation is easier, and beats the joystick. The finger marks are not a problem and nothing that can be take care by a swipe or two with a good eyeglass cloth. The surface is a mirror like finish at times somewhat reflective under bright sunlight. The leather hood LCD screen by Canon is highly recommended . I've used it and it really cuts down reflections.
LANC remote control--------I was really waiting for this one. I have a very old pistol grip from the Video 8 Era from Sony that has a LANC cable that connects to the remote terminal, and allows me to do the basic: start/stop, zoom in/out, on/lock/stand by. operations all from a firm hand grip. The grip also converts to a rock solid small tripod that is invaluable for certain table top shots. (see attached Jpeg).
HD to SD conversion in camera-------Very new feature, works as advertised, lets you keep the HD clips. You have a choice of bit rate for conversion, 3 and 9 Mbps bit rates. The higher the bit rate the better the quality of the resulting SD conversion. I did one conversion and produced a simple DVD that looked very good on my HDTV to the point that I had a hard time to see the difference between the HD and the SD project. The files of course are 740x420 the std resolution for SD.
STD, Dynamic and Powered IS----Dynamic vs the previous STD is definitely a major improvement and very welcomed, however the Powered IS is not working to me as a major change even if I use it only on the tele end of the spectrum. Maybe I don't know how to work it yet, but I don't see the major change as advertised when activated from hand held shots.
Custom Key and Dial ------ Not a new feature but greatly enhanced and more easily to work with the new Touch Screen feature. The custom Gain control has been expanded to cover more situations and choosing the feature that you want to control is now a snap.
Again with the Touch Screen it beats the joystick.
Surround Sound 5.1 Microphone------Very good, very small and very practical, works as advertised. My Onkyo receiver switches to Dolby Digital for decoding when playing clips recorded with the Surround Mic. Canon sends you a small SD card so that you can do a firmware update, before you can use the Mic, follow the included instructions. You can use Surround 5.1, Zoom Surround 5.1, and and Gunshot Surround 5.1 all with different audible characteristics, Plain Surround 5.1 gives you the best spatial sound-field by my own testing, but it is a matter of choice. The Mic comes with a wind muff.
Native 24p-----At last no more 2-3 pulldown !!!. What a pain. Never was much of a fan of 24p anyway but now I may learn to use it more often. Do 95% of my shooting at 30p.
Well, I still have more testing to do, all considered the Touch Screen is a blessing in disguise it allows you to use the major new features very easily, for example.... the focus shift in Tele from near to far or vice-versa is now very easy to use, among many other new features.
Hope some response is generated from this fully loaded new cam from Canon which is lacking from all Forums.
Thank You, Enjoy!!