SMPlayer, a Qt front-end for mplayer, has reached version 15.9.0 recently, this being the first stable version to support mpv. There are various other new features as well, like support for 3D stereo filter, MPRIS v2 support, a new default theme and more.
mpv is a media player based on mplayer2 (and MPlayer), which comes with extra features and improvements, like native support for VAAPI and VDA along with improved VDPAU video output, precise seeking, gapeless audio support, better MKV support (including ordered chapters, 3D metadata) and more.