Ok, I have to ask, who the heck takes pics at that resolution? I don't go around making posters, but more importantly if my artistry was that important, why would I use a camera phone???
Well, the simple fact is that it does not take 41MP pictures. That is not the point of having a 41MP sensor because (as you said) it would be useless in most situations. However, it does allow for a few very interesting things:
-If used as a normal point and shoot, you will typically be taking 5MP images with the camera with an effective ~6x anti-ailising built in. This allows for amazingly detailed pictures with very little noise and artifacts, while still rendering a 5MP image that will display and print well.
-Another use is for loss-less digital zoom. On the Pureview 808 phone (which had a similar camera over a year ago) you could give up some of the beautiful anti-aliasing in exchange for a 6x loss-less digital zoom. This new sensor supposedly has a 2x optical zoom in addition to the 6x digital, which should make a 12x zoom possible without loosing quality, and without a super thick phone in your pocket. With this you would give up some of the noise-canceling that comes with anti-ailising, but you still get a native resolution image rather than the stretched blurred trash that is produced by most digital zooms.
-Lastly, this helps a lot in low light situations. When you do not have a lot of available light on cameras with small sensors (like phones and point-and-shoot devices) then it is common practice to take the light from multiple pixels and bind them together. For most phones this means a drastic loss in resolution and clarity (similar to digital zoom), but in the case of this phone it means giving up some noise reducing anti-aliasing in order to boost the signal and still getting a beautiful native resolution image.
However, the real secret sauce to this camera over the old Pureview 808 is the OIS that is included similar to the camera in the Lumia 920 which I have. OIS is really just a fancy ways to say that they put isolating springs between the sensor and the phone body, but it makes a pretty big difference when it comes to taking pictures (particularly in zoom or low light situations), and makes a monumental difference when taking video while moving. With my 920 I can literally run (as fast as my nerd build allows) with my phone while capturing video of my kiddos and still end up with a video that is watchable when even most video cameras with digital OIS would not be. It is a big deal, and should be even better in the 1020 coming out.
Bottom line; If you are a hobbyist or professional who has a nice DSLR camera and you like to go out on shoots then this is probably not a device you would be interested in. I mean, as good as it is, we are still talking about a camera phone; the whole device is expected to cost ~$600 when a DSLR generally costs that much just for the body. However, for someone like myself who has 2 kids, and sometimes has to take some decent pictures to document things as work, it is invaluable to have a pocket-sized device that I can use at a moments notice with very little prep time.
I am frankly (and unfortunately) not nearly good enough of a photographer to justify spending a bunch of money on a truly decent camera with good lenses. However, if I need a smartphone anyways (which I do for work) then I can easily justify spending an extra $1-200 for a smartphone that is going to give me good pictures. It is a no brainier for people in my situation.
What I don't like however (and is the reason I will not be upgrading), is that other than the camera and an extra GB of ram to support the camera, this phone is identical to the 920/925/928 that we have already seen. I was really hoping that this would just be a product announcement for a Christmas. Some time this fall MS will be releasing their GDR3 update which will allow for 1080p displays and a wider variety of CPUs (including quad core CPUs). I have a 920, which means that other than the camera I will have all of the other features that this phone provides. When I can get a phone with this camera that also has 64GB of storage, a 1080p display, and a quad core (or preferably just a faster duel core) CPU then I will happily fork over the money for an upgrade. But to purchase what is essentially the same phone that I already have outside of contract? That does not fly so well. The phone I am hoping for may still come out, but it is certainly not this one.