Have you used coinbase?
Yes.
Can you make money here or is it a waste of time? Is the site secure?
Many traders have been using that exchanges, it's one of the most popular trading sites we currently have. But as far as security, we can't say how secure a site is, because there will be hackers that are going to attempt to attack any system that we have right now. You can read this article,
Coinbase Sets Out How It Foiled a ‘Sophisticated’ Hacking Attack.