Well. In fairness the novel itself is not all that bad, just very ordinary; our viewpoint character is a beautiful aristocrat bred for a submissive personality (which she is able to overcome just sufficiently for the needs of the plot); she is loved by another aristocrat who is from a different planet and conceals a heart of gold under his rugged exterior and alcoholism; and a third aristocrat envies them and tries to break them up by raping her. Our heroine then goes to her lover's home world where they discover a lost city which his people had carelessly forgotten about. Also the nice aristocrats are locked in conflict with the evil Earth people. Then we find out in an afterword that the entire novel is a metaphor for quantum scattering theory and the three characters should really be considered as elementary particles (I am not making this up).
I guess the kindest thing that I can say is that this sort of thing is simply not my cup of tea; and I think on reflection that among Nebula winners The Quantum Rose is not quite as bad a novel as Robert Sawyer's The Terminal Experiment, and roughly as bad as The Gods Themselves.
I have read four of the other Nebula nominees for 2000 - A Storm of Swords, by George R.R.Martin; The Collapsium, by Wil McCarthy; Declare, by Tim Powers and Passage, by Connie Willis. The last of these is also pretty ordinary, but any of the other three would have been a more comprehensible winner - my memory is that The Collapsium is a bit disorganised but fun. The other nominees were The Tower at Stony Wood, by Patricia A. McKillip; Eternity's End, by Jeffrey A.Carver; and Mars Crossing, by Geoffrey A. Landis. I don't think I have heard much about any of these. The Hugo for the relevant year (2001) went to Harry Potter and the Goblet of Fire with the other nominees being A Storm of Swords again, two other good books - Ken MacLeod's The Sky Road and Nalo Hopkinson's Midnight Robber; and a Robert Sawyer novel. All but the last of these would have been more comprehensible Nebula winners.
OK, just one more to go - Powers, by Ursula Le Guin.