I bought this camera about a month ago (not sure exactly when). They were available at certain Best Buys and I got one that way. I did not have a S95, and I had not used a point and shoot for quite a while (I have been using a T1i for the last several years, and got a 5DMII a few weeks ago). After about a week with the S100, I returned the camera. Shooting stationary objects in good light produces good results. Otherwise, I found the camera to be pretty much unusable for any of my needs- my breaking point was taking it to a Halloween zoo event to take photos of my kids. The shutter lag was incredibly slow.
lol, it's kind of funny - I totally understand where you're coming from, it's dog slow compared to a snappy dslr (a good dslr with a decently fast autofocus lens). On the other hand, my dad recently tried shooting with his 5-10 year old Olympus compact, and remembered how much slower cameras used to be, lol.
None of the focus modes worked well for me- with a point and shoot type camera, I can really see how a touchscreen would be useful in picking a focus point.
One common mistake dslr users make when moving to a compact is getting really paranoid about the focus point. On a dslr in low light, the focus point is completely critical, if it's even a little off it ruins the pic. But a compact even at f2.0 has a *much* larger depth of field where the focus point is *far* less important. If your subject is anywhere near the middle of your shot, you're good.
If your subject isn't near the middle of your shot, the technique that's used is to put frame the camera so the subject is in the middle your shot, then either half-press the shutter or assign the shortcut button to focus lock and press it, then move the frame to how you want it and take the pic. With a smaller sensored camera the very slight difference in distance you create by moving the camera over is completely unnoticeable for focus (whereis with a dslr and f2.0 it can screw up your shot).
And fyi, that's the fastest way to do it. A new feature on the s100 is to use FlexiZone to move around your focus point on the screen.
Shooting people in jpeg, there is so much in camera noise reduction applied, people look ridiculous.
I kind of agree with you - it's the effect of the new noise reduction on the s100, the s95 used a totally different kind of noise reduction.
You can turn the noise reduction down in the camera to "low", but you still get some of the effect. If you shoot raw and convert with Canon's software you can turn detail noise reduction off, which is what I'm leaning towards doing. And I'm not sure what Lightroom will do, but it will probably give you more options.
It's funny, I didn't really like it's effect when people are in the pic. But I showed comparison pics with noise reduction on and off and they usually preferred how it looked with noise reduction on, so...
I do wish there was an in-camera option to turn noise reduction "off".
I honestly think that it has to be me, but I just do not get the following this camera has. I think if you have cooperative subjects (vs. small children), and shoot in RAW, your results are probably better. Awesome ergonomics, very pocketable, I loved the feel of the camera, but for me the everyday results were pretty awful. Some of my macro shots, of objects, were really, really good. But that is not the situation I want a point and shoot for. Since I don't really care about pocketability so much, I think another option (m43rds? X100? I have no idea) would be better for me. I also really forgot about shutter lag- like it was disorienting. I suppose that any camera that is not a DSLR probably has that though, to some degree.
The vast majority of compacts have similar amounts of shutter lag.
There is one that I know of that does not - the Panasonic lx5. It's not "jeans pocketable", but it's still "could possibly cram it in a jeans pocket would just be really uncomfortable to walk around like that" sized.
Imaging resource's timing gave it's shutter lag timing almost the same as an entry level dslr - and more importantly I tried it out myself at my local camera store next to a Canon t2i and could not tell the difference in focus speed (unlike the s95, g12, and Nikon p7000 where I could tell the difference in focus speed). The lx5 has similar low light performance to the s100 (though not the s100's new noise reduction, which sounds like it would be a plus for you).
The other option is that the new Nikon Mirrorless system touts itself as happy instant autofocus (Nikon System 1 I think). It has a 60fps full resolution shot rate, so it's plausible. People hated it when it was announced because it's sensor, while noteably larger than a compact, is smaller than m43rds. The other big drawback is that it's best low light lens if f2.8. But if autofocus speed is your priority...
The latest Olympus m43rds cameras claim near-instant autofocus...but from what I've read that's only with the latest Olympus lenses, with the Panasonic f1.7 lens (the low light lens one would use for m43rds), it's not as fast, though it could certainly still be faster than the s100 (I don't know personally).
The newly announced Panasonic gx1 (I think that's the model number) uses Panasonic's new m43rds sensor which is better than the older one in the Olympus m43rds cameras. However, their m43rds aren't known for the snappy autofocus speeds, and they even only claim like a 10% improvement in the gx1.
The Sony NEX wasn't known for instant autofocus speeds, and it's best low light lens is unfortunately f2.8 as well.
The Samsung nx200 looks promising, it's so new there's not much info on it's autofocus speeds. Samsung claims 0.1 seconds (instant), I don't know if this pans out or not. They do have an f2.0 prime lens available right now for it, though.