I'm an iPhone fan, and have had several. The primary reason I ever get a new one, is that the cameras are getting better by leaps and bound. They never compare though, to a good DSLR. However, the best camera you will ever have, is the one you have with you. That being said, I do not carry a DSLR around with me, but my phone is usually in my pocket.
Low light/night pics suffer with any camera though. The lower the light, the more grainy the picture. Some of that could be cleared up with an ISO adjustment and shutter speed tweak, but that only goes so far when the light is dim.
Try wearing a headlamp while taking night pics, but beware of casting phone-shadows on your subject.