Sentinel-2 is an Earth observation mission developed by ESA as part of the Copernicus Programme to perform terrestrial observations in support of services such as forest monitoring, land cover changes detection, and natural disaster management. It consists of two identical satellites, Sentinel-2A and Sentinel-2B.
This is the description of Sentinel-2 from the respective page in Wikipedia. This mission will be a great alternative to Landsat or the paid SPOT images, providing images in a great detail and frequency, for most parts of the Earth.
Coming down to some technical details, both of the satellites, Sentinel 2A and 2B will provide multi-spectral images, within the latitude of -56 to +83 degrees (whole Earth, excluding Antarctica), in a resolution of 10m, 20m and 60m and a FoV (Field of View) of 290km. There will be 13 spectral bands that will be covered, including 3 for atmospheric corrections.
Sentinel-2A was launched in June 2015, while Sentinel-2B is expected to launch within mid to late 2016. There are some images that can be downloaded from the website of European Space Agency or directly from the awesome semi-automatic classification plugin for QGis, which was updated to be able to download data directly for analysis.