I think that you should take anything with a grain of salt that says that it speeds up your metabolism. The only thing that is guaranteed to speed up your metabolism is eating healthy (cut out the junk, starch, sugar, etc.) and exercise.
Anything that claims to speed up your metabolism is probably loaded with caffeine or stimulants found in chocolate/tea, such as theobromine or theophylline.
Consuming caffeine affects everyone differently, but one thing for sure, the energy that caffeine gives you is energy borrowed form your adrenal glands. And you will pay the price with a crash afterwards.
It is also best to always do as much research as possible on any supplements, you are putting these in your body.
As for the creatine, I would search the posts for that information, there has been a lot posted here.