No offense, but if you don't research a product before you buy it you deserve to get ripped off.
Seriously all you would have to do is go to IGN.com and read the review (text or video) and you would find out they said this for "hardcore halo fans" and that the storyline is only 6 hours and that its not ment to be a full new title but rather an expansion and the downside was that it carried a 60 dollar price tag.