That's exactly it -- low lighting situations are terrible. The year-old HTC Thunderbolt I used to use was better (and also higher resolution). But mostly, if you compare the image quality to the iPhone 4S, it's a no-brainer. The iPhone destroys the GN in image quality.
BTW, brings up another thought: I'm pretty sure Android is more aggressive about JPEG compression by default than iPhone. I haven't thoroughly researched this except to notice the relative sizes of files the two generate at the same resolution.