A couple of things annoyed me...
There was no background score at all, i mean how can you get the audience in the mood with no music? The sound effects were at different sound levels and were not the best quality, you would had done better recording your own SFX.
The animation wasnt bad apart from the replaying, you showed the icicles "sparkling" then proceeded to show it again and again. You only have to show people once that "this object is pointy and sharp". You dont need to show it 4-5 times to let the audience understand that, in fact i dont think any effect was necessary as the audience will understand what going to happen anyway.
This animation could be done much better, and it shows how useless those "beta viewers" you showed it to were not to tell you that.