Try it. Z-Brush is amazingly powerful, but I would not say that it is easy to get excellent results. Depending on talent this will require lots of practice. I would suggest to download the free Sculptris program: http://www.pixologic.com/sculptris/
Z-Brush is basically Sculptris on steroids (big time). If Sculptris works for you, get the free demo for Z-Brush and see what it can do. They have lots of video tutorials on their website. Watch those. It gives you a idea what can be done and how much effort is needed.