Hi all,
I'm now 7 weeks and about 1,500 exposures into my new S5 IS and I have some definite opinions at this point.
I bought the S5 as an upgrade from the S2 rather than buying a dSLR (XTi and Olly E-510 were my candidates) so let me start with I'm a SupreZoom fan. I'm too lazy to lug around a backpack of stuff. Also, I'm really not advanced enough to fully utilize a dSLR yet.
Anyhow, I really like the lens on the S5 (same as the S2) BUT I kind of wish Canon had left the S5 at 6 MP like the S3. The 1/8th sensor is definitely done. The S5 takes seriously good images but I find myself using Noiseware a lot more than with the S2. Other than that, IQ is a bit sharper than the S2/S3 and, if you kill the noise, you can crop a bit better. That's important to me since I'm not yet great at in-camera composition. If you want, take a look at the S5/S2 side by side on either of my sites.
I finally got to use the face detection this weekend and it is really a great help. I took a bunch of exposures in a dark bar room with stage lighting and the S5 not only focused on the faces but seemed to modulate the on-board flash fairly well. I got about 25 good out of 35 shots and that's the reverse of my usual ratio.
I haven't used the hot shoe yet (my other reason for upgrading) but I have a 430 EX on order so I'll let you all know in late September what's up with that.
Battery life is as good or better than the S2 even with the 2.5" screen (rather than 1.8"). I shoot thru the EV but I review everything with the LCD so I do use it a lot.
I also like the digital teleconverters (1.6 and 2.0) although the standard 48X DZ is still a mess (at least in my hands). In addition, the live histogram, rule of thirds grid and 4x3 outline are really welcome aids to me. You may or may not care about them, but I love 'em.
On the downside, I'd like to find the guy who put the SD card in the battery holder and beat him with a stick. I don't use my reader anymore, just hook up a USB cable direct. Bummer. Also, although the tripod mount is upgraded to metal, you cannot change the SD card on the tripod.
All in all the S5 upgrade is suiting me really well. I'm still not sure it's worth upgrading from the S3 but the FD, Hot Shoe and the EV grid and Histo are a huge plus in my personal learning curve. Once I get the 430EX I expect to spend another year learning some more. Maybe then I'll be grown up enough for a dSLR. Or maybe not.
If anybody out there is on the fence about the S%, I hope this has helped you. Most of the stuff on my Pbase site is S5 if you'd like to go there.