WebMD has a lot of articles praising the health benefits of green tea, but none for that diet pill. Maybe you clicked on one of the ads instead?
I think the reason for the mixed reviews is that green tea really doesn't do what they marketers would have us believe. The actual published clinical studies show that the weight loss from green tea is very minimal, hardly enough to be noticed. (up to 8 lbs over the course of a whole year) Also you must drink real green tea to get the benefit, as the pills have not been shown to do anything.
Supplement marketers are not currently required to prove their claims. Sadly that makes it very difficult for the rest of us to sort out the truth from fiction.
Find a good green tea that you like the taste of, and aim for 4 cups per day.
Search this forum and you'll find a lot of posts from other members that have tried the green tea trick without results. However, they still drink it for the antioxidant benefit. Also a lot of people find drinking calorie free beverages such as tea help to keep from consuming other foods with calories. In that respect, it can and does help with weight loss.