Honestly, Dawn should've won and the writers should've developed her more rather that spending so many episodes on CoTDs.
Not to mention, what's really stopping the writers from letting our "heroes" win tourneys? It's simple: develop the characters so they win a great victory? And just because Ash, May or Dawn win, it does NOT mean that they're story is over. There are still more leagues, GFs and trainers for them to beat all over the world. Plus, all the Pokemon for them to catch and train. Why would they stop training just because they're the best in one region?
This isn't very complicated, PEOPLE!
As for this episode, it was good but I felt that Dawn's loss ruined it for. I really wanted her to win and see her happy. Sure she took her loss well and that's great but I still wanted her to taste the sweet flavor of victory.