After almost 5 years I was getting tired to carry around my heavy bag with a 350D and a Sigma 17-70 and sometimes another 70-300 lens. So I did miss lots of shots as the camera was home. As people say, the best camera is the one you have with you I gave it a shot to the new S90. In case you have been tempted about the same here comes my thoughts.

On the positive side:
- The IS is amazing, in some cases I could take better pics than with Sigma 17-70 without that doesn't have IS. Even at 1s exposure time I mannaged to get pretty sharp shots.
- Nice feature to have the object in focus zoomed in
- Surprisingly good flash
- You can actually carry the camera in the pockets of your pants
- Daytime is hard to distinguish IQ difference on screen resized images. You need to pixel peep for that
- Very easy to use manual modes, just as easy as on DSLR, that was a positive surprise

Negative
- Although this was a camera that is supposed to have good low light performance I find the results pretty bad, sometimes closer to a cell phone than to a DSLR. It's not the noise, everything is just blurry and messy if you don't use flash.
- It's impossible to get the auto mode to focus on what you really want. Although this is pretty difficult on the 350D as well
- The DOF is always huge, forget portraits with blurry backgrounds

Conclusion
If you know its strengths and weaknesses I think you can leave the heavy DSLR bag at home some days. Daytime in the city works great. At parties use flash. Night time carry your bigger bag with you.