Yeah, my upper body and leg muscle mass increased within the first month, not massively, but it was noticeable... about an extra 10%. I wasn't working out at the time. I am stronger and I definitely have a better aerobic capacity (from increased blood cell count). Now that I'm working out, yeah, I'm definitely seeing results in strength and stamina.
In terms of losing weight, it's easy to lose weight on T just by knocking off a few calories from your regular intake in my experience if you aren't working out.