I might not have seen all the city skylines in the whole world, but is there a need after this? Of course the view is still not as good as that from Victoria Peak, but then this is so accessible - just a ferry ride, an MTR ride (get off at Tsim Sha Tsui station and walk south), a bus ride, or a stroll from the MTR Hung Hom station. more about TST promenade - the location with this view
Photo tip: if you just want to take a photo of the view at night without any people, turn off your flash and hold your camera very still, or use a tripod or set it on top of something. If you want to include people, set your camera to 'night portrait' mode (it's often indicated by an icon like that to the left - a person with a star behind). But be sure to hold the camera very still for a few seconds after the flash goes off. Otherwise, you'll get a blurred background.
If you'd like to enjoy this view from your hotel room, there're a number of hotels with harbor view rooms in Hong Kong. But of course you'll need to pay a bit more.