This is pretty good! I know how hard animation can be, seeing as I was forced into doing animation for a startup game company that, for the three years I was "working" for them, never completed a single game nor paid me for most of my time, but all the animations I did were just animated mouse cursor loops that weren't even this long and those still practically kicked the snot outta me. I'm thinking you might've used a bit TOO much motion blur (as FinaLee said earlier), but outside of that, this is smooth as silk!