I've seen this episode in the UK and here is my review:
Voices: Excellent. Michelle's and Bagon's voices were brilliant. Bagon's voice was exactly the way I thought it sound like. Same goes for Shellgon.
Pokemon: All pretty good. No new attacks here, so not much to say.
Characters: Michelle is an excellent character and I'm not suprised she made good friends with Ash, with her powerful and determined nature.
Content: By far one of the best fillers I've ever seen. As always, there are some funny bits dotted here and there in the episode. I loved the battle between Pika and Bagon, Pikachu's Matrix duck rocks! The battle was shown brilliantly and Michelle's glasses really gave her the advantage, but she can't come over Ash's strategy!
Overall, a very good filler. 9.5/10.