Is it worth it? No...
Arginine has been shown in studies to increase, but I've never heard anyone say they noticed a substantial difference. Note that studies show most manufacturers recommend far less than the amounts that have been documented to be most effective.
While ornithine does appear to at least temporarily increase levels of growth hormone, claims of greater mass and strength are questionable. A more probable benefit may be improved recovery by flushing ammonia, a toxic byproduct of exercise, out of the body.