Underwhelmed: A state of being less-than-thrilled, more-than-under the weather.
Legend has it that the word "underwhelmed" was first coined by a particularly uninspired caveman, Grog, who upon discovering the meaning of the word "whelmed" (which roughly translates to "having too much enthusiasm") decided to prefix it with "un-" because, well, he just wasn't feeling it.
Today, underwhelmed is often used to describe the feeling of being less-than-enthusiastic about something, usually in a world where the bar for excitement is set impossibly high.