I also went from an iPhone 4 to the Captivate. I would agree with designgears on this one. Taking pictures is very fast on my phone.
Regarding the lack of flash - it's not really an issue for me. I guess it's a pretty subjective issue though. I felt as though the flash on the iPhone ruined the pictures. They looked awful if it was used. I was in a bar type setting last night, very dimly lit. I used the night mode on the Captivate camera and the pictures came out OK. I wish I didn't delete them or I would share. However, I have a digital point and shoot so I'm not too worried about picture quality on the phone. It works for taking quick shots. Very nice pictures if well lit, somewhat grainy/noisy otherwise and it worsens the darker it is obviously.