Thousands of different opinions on this one but bottom line is: you can only go so far with body weight exercises. If your goal is to build some mass and serious definition, you'll have to pick the weights up. Just remember to stay with the basics; squats, bench, barbell row, overhead press, and dead lifts. Don't get lured into doing the small pussy exercises where you isolate a single muscle group, it's pretty much a waste of time. If you reach a competition level physique, those exercises will crank out the last 1% of your definition, but until you're there you need to establish the foundation of your body work with the basics. And more so, you'll never get ripped if you slack on your nutrition quality. Stick with a stellar nutrition plan, or all your effort with the weights will only get you so far.