So far so good. Black levels are definitely better than the Samsung, but overall picture quality is pretty much on par. I also appreciate the lack of reflections on the ST50, it really stands apart from the Samsung in this respect. Colors are a tiny a tiny bit more saturated, but other than that, both are outstanding looking sets. What's really winning me over is the size, 55" is right where I need to be.
Also, someone commented on the Samsung being dim, I disagree, if anything, it (Samsung) might be just a tad brighter (both using their respective cinema/movie modes).