The first scientific results regarding the Pluto system as observed from New Horizons have been published in Science [1]. It is impressive to see direct images and maps of such distant worlds.
More remarkable is the complex geology and geomorphology which characterize both Pluto and Charon. Pluto is by far a non-dead planet as resurfacing is indicative is some areas, which is puzzling as there are no obvious energy sources for such activity. Moreover, water ice may be the basis for the formation of high mountains (up to 2-3 km) as N2, CO, and CH4 cannot form such structures.
Pluto’s atmosphere, as measured by solar UV absorption, is characterized by N2 at ~1670km, CH4 below ~960km, C2H4 at ~300km, haze below ~150km, and C2H2 at ~50km. Additionally, UV and high-energy radiation interact with the these particles giving raise to tholins (a form of organic molecules).
The other two moons to be observed, Nix and Hydra, displayed high albedo, probably due to cleaner (compared to what is found in Charon) water ice – another puzzling issue since there is a number of processes that could darken their surfaces (like transfer of darker material from Charon or Kuiper meteorites).
More results are forthcoming, since there are data (e.g. UV spectra) that have not been downlinked from the satellite yet.
[1] Stern et al., 2015, Science, vol. 350, 292,
or arXiv:1510.07704