A year ago, I would have called these pictures outstanding. Unfortunately, now with the cameras that Samsung and Apple are bringing to the table, and their quality in low light, these aren't too good. However, we are talking about a CELL PHONE here, not a camera; people shouldn't be using their phones for professional pictures anyways.
Some of those photos are indeed quite noisy - which I guess indicates high default 'ISO' settings? (Open to being corrected by those with more experience here).
I'd be very interested to see if there are any apps on the WP7 marketplace that can deliver better results here. Does anyone know if Windows Phone has HDR, or if there are any apps that can deliver HDR, or even apps that allow more control over the camera?
There's maybe an opening here for Nokia to do some more 'value add' to the Lumia by launching their own camera & photo app to help deliver better results. Maybe it's something to offer feedback to Nokia on?
As I'm not a photographer, this sort of image quality is just fine for me - particular when combined with one of the many apps that /are/ available that offer picture enhancement. So, it's still a Lumia 800 for me