I think Jonathan Chait has it just about right.
If health care passes, will it be a grand historical achievement, or a crushing disappointment? The answer, I predict, will be both. The American health care system is an indefensible morass of waste and cruelty. The distance between the status quo and the ideal is therefore so vast that we could—and probably will—end up with a reform that massively improves the system, while coming nowhere close to the ideal.