I feel like it's fair enough. Like Humpstyles stated it only lasts for 3 seconds and has to recharge, and there are ways to counter it. It's unknown at the moment whether one of these methods would be the Hologram or not, but it's safe to assume it is. It also doesn't make you invincible. Keep in mind that when you use Promethean Vision, a majority of what you're seeing will be in a linear fashion. Granted, you would be able to turn and see an enemy to the side of you whilst using Promethean Vision, but once again, you only have 3 seconds and in that time most of your attention will be focused on your initial target. So, if someone comes out beside you while you're using Promethean Vision, you're through.