The camera on this device isn't supposed to be just good enough.
It depends where you come from. I'm not surprised that N8 is capable of taking better pictures in some scenarios. Not to mention the 808. While this is a current camera flagship, but it's camera flahshippyness comes mainly from the optical stabilisation which doesnt get to show off it's best in every possible scenario.
I cant take good low light pictures on my N8 except with flash, but it ruins any of the possible low light setting with overexposure, but the xenon flash sure lights up the whole bedroom as if I had every possible light on lol. I dont have any "reliable statistics" here how often I have to retake my picture cos my hand shaked a bit at the wrong time and the picture ended up blurry, but I'd say at least a few times in every 10 photos at the very least. Not to mention in videos it's a constant problem.
This still blows away vast majority of smartphone cameras, with really the only competing ones being the previous camera flagships from Nokia itself. Some LG I think had 13 mpix camera, but that wasnt really impressive photos either.
That said, this still doesnt represent the absolute highest of camera tech Nokia has had. I still see Pureview 808 more so for that, the only special thing the Lumia 920 has going for it camera wise is the OIS and low light images, in which it currently has no rivals in.
That said, it's not like I'm even getting the 920 for it's camera. I'm more so getting the 920 despite it's camera, I can see myself still carrying my N8 at least in my schoolbag SIMless for the times I need higher res pictures for my certain personal niche needs. It depends on how well I can photo 2 pages of ~A4 size papers (basically the average university book kinda thing) with the 920. If they remain well readable and I dont have to compromise, then I probably wont carry the N8 around anymore, but I wont be surprised even if N8 ends up better for the job, sadly when copying books like that, blurry pictures is what wastes the most time, so for that OIS is God sent, so I'd hope the 920 is sufficient for that too.
In a way I feel what you are complaining right now is quite similar to some of the Surface reviews, where they complain how the kickstand is hard to use on lap and how the assist is only on one side while completely ignoring the feature of the kickstand which it's competitors dont even frigging have lol. No, you can't be best at everything, I'm not surprised if phones with big camera bulges do better than the Lumia 920, but even then the Lumia 920 has features in it's camera that in certain scenarios beat fe. even PureView 808 but at least N8.