As usual, I'm fashionably late to the party but I finally watched the film!
Personally, I felt like the plot was stretched a bit thin, which was something I was concerned about when the trailer came out. There were a lot of new characters (and locations) introduced, all very interesting and with a lot of potential but there just wasn't enough time to develop them properly - except Tempest. Who completely stole Storm King's thunder.
I can't praise the animation enough though, it was so beautiful. The MLP animators could give anime producers a run for their money, because those sparkly eyes were so pretty they were practically shoujo-level.