Is it legal to run a website that reviews other companies products and uses their images?

So I’m thinking of doing a website that reviews products. My question is, how legal is it to take information (images, screenshots, youtube videos, etc) from someone else to review their product? Here’s an example: http://www.famigo.com/ They review lots of mobile apps for kids, using a lot of resources (images, etc), that they took from other people. Is this okay? If so, is there anything to watch out for so I don’t break copyright rules, etc?