I bought an A570is for this purpose, which is essentially identical to the A590is. Battery life depends on your batteries. I love rechargeables, but for this camera I eventually just sucked it up and bought lithiums. They last forever, I keep the camera in my work bag in an $8 case for those "wish I had a camera" moments, and I've had the same batteries in there for almost 6 months. This has included a few "girlfriend forgot her camera and used mine to get awful facebook bar shots all night" uses, as well as my usual once weekly "ooh, pretty" uses. Feels cheap and plastic, because it is cheap and plastic. Not terribly fragile, mine has fared better than mother's/girlfriend's/sister's canon SD series cameras (stupid lens extension issues).
Like:
*Price; cost me $140 with 2gb card a year ago
*Image quality - as much as one could expect for this price, and with enough light/low dynamic range it can produce files identical to my old D100 and D70 bodies in prints
*Customizable RAW, live histogram etc with CHDK (see below)
*Some decent manual control if you're caught in a "shoulda brought the real camera" situation
*IS isn't useless, but it doesn't make up for the lack of ISO performance worth beans over 200
*Auto-ISO is handy for the kind of shots I use it for
*It's small enough to shoot through chain link (like any compact really)
*With my tiny gorillapod it can get low light shots...dynamic range is minimal, but it can get the shot plus let you choose shutter speed and aperture without menus
Dislike:
*lens range is awful for me; Lumix LX3 would have been a better (and much more expensive) fit in that regard. If you'd use a 35-140 or equivalent lens on your SLR you're set, but I use ultrawides for at least half my shots
*Flash is slow to charge compared to SD series with their better batteries, and the flash doesn't expose faces in dark rooms without overexposure very often (luckily there's some adjustment available)
*Not pocketable except in jackets, the SD series are more expensive and have no real manual control but you can literally stuff them in your pants...assuming you don't wear really really tight pants...
CHDK is a little firmware addition you put on your SD card which allows you to customize a million things (too many really, but it allows raw shooting and a live histogram which I enjoy). They have instructions on their main page
here, but it doesn't screw with your real firmware at all, and although you have to convert the finished raw files to dng with
another program (there's a mac port) to use them (actually a few converters work, just read the page) I still find it worth the trouble for any shots I'll care about.
In reality you aren't going to see a huge difference in quality from raw files. They're only 10-bit to start with, but I like the control, particularly in noise reduction. My raw files always end up noisier than camera-processed jpegs, but they have more detail and I prefer them.
I bought an SD1100is for my sister (yes, pink) this christmas, and suggested them to 3 others who also bought them. Great cameras, and fantastically portable, but if you want any control they're not the ticket. The SD880is has a nice wider range if you're considering the 1100.
Sorry for the novel, hope it's at least mildly helpful!
