Jonathan Strahan thinks there is no such thing as "the new space opera," but, prodded by Ellen Datlow in comments to that post, is now asking others to tell him what their definition of space opera is.

For myself, a space opera is a science fiction story involving space travel (preferably at least interstellar) in which the stakes are high and the audience is expected to be rooting for someone in particular to come out ahead in the end. It may or may not be well-written; it may or may not tackle larger issues. Space adventure without anything important (above and beyond the character's own lives) isn't space opera, to my mind. Stories set entirely on planetary surfaces also don't count -- those may be planetary romances, a related category, if they're otherwise similar to space opera. I think it is possible for a story to be both space opera and Military SF. Quality of science does not matter in space opera; in fact, I've always said that quality of science is rarely important in a SF story worth reading.