The primary camera on the Asus ZenFone 5 was a competent performer. Unfortunately, Asus has failed to recreate that on the ZenFone 2. We consistently saw mediocre results with the 13-megapixel shooter, which should have been more powerful than the 8-megapixel one on the ZenFone 5.
The average image quality of the ZenFone 2's primary camera is yet another reason for us to reiterate that the megapixel count doesn't directly correlate to camera quality.