Instruct: Classify a given Amazon review as either positive or negative.
Query: Great size but loses air

The title says it all. Overall the size and weight was what I expected after reading other reviews. My guests slept great and thought the firmness was superior to past experiences. The mattress did lose air overnight and even when not slept on, it required additional air each night. The valve does not cap off like some other models, which may be the problem.