Yeah those rallies were awesome, Zvonareva in particular doing some stellar retrieving. However, I kind of got the feeling that the rallies were so long more because of the nerves of both players (scared to put the ball away, hoping for the error from there opponent) than anything else.
So from that point of view, the quality wasn't that great in that last set.
Of all the qfs (in terms of BOTH players giving quality) it probably was the best, along with Henin/Rubin. That wasn't a very exciting or emotional match, but they both played at similar levels for most of the match, and good attacking tennis.