Much has been said about HTC's camera in the M9, but it ultimately comes down to this: It can take some really good pictures, if you're patient and don't mind getting out of Auto mode and shooting more manually. And today M9 mobile photogs have gotten a pretty big boost to their phones with the addition of support for the RAW format, which gives you far more control over the editing of a shot (while getting rid of the compression that comes along with JPGs).
It's just a simple update of the HTC Camera app in Google Play, and from there you'll choose "Raw camera" in the modes screen.
As for image sizes, well, RAW files take up a lot of space. Getting close to 40 megabyte per picture isn't out of the question here, folks. The good news is the M9 can take an SD card to go along with that 32GB of on-board storage.
While the RAW update is only for the M9 at the moment, the app does add Crop-me-in mode for the HTC One M8 Eye and Desire Eye phones, and you now have the ability to remove modes if you don't use them.