well, there is no debate......its good for both of course.
aside from some insulin, it is pretty much entirely responsible for the leaner, yet more muscled bodybuilders that you saw start to pop up in the early to mid 80s spanning to today, compared to guys in arnolds time.....they had a totally different look (steroids no HGH)
at low doses, 5 IUs and under, it will keep you very lean, pretty much regardless of your diet.....an will give your muscles a compleatly different, harder, granier look
at doses above 5 IUs, it will keep you even leaner than i mentioned above, but will also begin to add muscle, by both hypertrophy (larger muscle cell), and by hyperplaisia (makes new muscle cells).......the latter, hyperplaisia, is a phenomenon unique only to HGH, steroids only cause hypertrophy.
to see these benifits, one must be willing to make a both a financial commitment and a time commitment..........Huma n Growth Hormone is almost useless if you dont give it at least 3 months or so.......i recomend staying on anywhere from 6 months to a year to multiple years if you can afford it.