Neptune is, along with Uranus and Saturn the most important planets in the solar system, due to their abundance of Helium-3 located with them, some scientists consider these planets the "Persian Gulf of the Solar system".
Neptune, like Uranus is a Ice Giant, meaning that an Abundance of Methane Ice have been located in the Atmosphere, it also has a deeper blue colouring in the atmosphere. Neptune, unlike Uranus has high speed wind storms in the atmosphere, and clouds that form in the atmosphere, making it easy to tell the difference between Uranus and Neptune, questionably there is alot of heat generation internally in Neptune.
A notable feature in Neptune, is the Great Dark Spot, compared to the Great Red Spot on Jupiter, this spot is pretty well the same, but differences are that they vary in size, they are both anti-cyclonic storms, and both obviously move about in the atmosphere. Uncanningly the dark spot was located in the southern hemisphere, however when taken a photo of again by the Hubble Telescope, it disappeared before everyones eyes, this led to believe that it was either covered up or vanished, later on an almost identical storm formed in the Northern Hemisphere.
Neptune has a good system of moons, however, it has been led to believe that most have been snagged from the Kuipers Belt. A notable Moon located in the Neptunian System is Triton, a Geologically active moon, it has been long under study, and if a Helium-3 Mining Corp were to set up base camp, this would be the logical choice in were to stay.
Mining wise, it would be smart, low escape velocity, low radiation levels, however, this can be questionable due to the high wind storms, and its remoteness from earth.