The iPhone 6’s rear-facing iSight camera is 8 megapixels. Some might argue that more would be better; we saw the megapixel race in point-and-shoot cameras, however, and we know how senseless it is. Megapixels represent quantity, not quality. To get more megapixels, manufacturers carve the image sensor up into smaller pixels that take in less light. That typically results in larger photos of poorer quality. That’s why Apple made the choice not to go for more pixels, but for bigger pixels — 1.5 microns at f/2.2. Because they’re larger, they take in more light and result in better-quality photos.
If you really want to shoot images sized for posters or billboards, or want to take advantage of significant downsampling, it’s okay to look for megapixels. If you want truly great photos, however, you’ll need to look beyond them.
Great snippet from Rene Ritchie explaining the myth around megapixels. Quality over quantity.