Comment Eu Contraire (Score 1) 398
My experience with VLC is that it has handled everything i've thrown at it admirably, with the few exceptions being horribly corrupted beyond recognition.
Mplayer will open and play more, but suffers horrible A/V desynch which, despite months of soliciting and applying arcane fix ideas, has remained persistent.
VLC is currently the only playback solution which can handle HD H.264 matroska without a major malfunction, and additionally has the highest quality video rendering, with more detail, smoother pans, and finer grained video controls than competitors.