Instruct: Classify the given Amazon review as either positive or negative.
Query: Was great until it broke

I purchased this product last week and when I first began using it it was great. It kept things hot, was spillproof, etc. When I was at work it tipped over on my desk and exploded (there was coffee EVERYWHERE). The top was appropriately sealed and I had closely followed the instructions for use. It was my third time using it. The top is broken now and the mug is completely unusable. I was SUPREMELY disappointed with this product.