No it won't make you bigger. I've not tried tribulus but have used a natural test booster when I was goin to the gym.
If it's anything like the stuff I had then it will make you horny as fuck, so much so it was not comfy, that was taking double the dose however.
Hair will grow faster, plus I developed hair where I didn't previously have it.
It's only worth taking if you work out just to give you that extra drive.