yes both positive/negative
Well, assuming your estradiol is properly managed, the biggest side risk for a young guy like you would a) loss of fertility, b) potential acne, etc.
There are other anecdotal reports: some guys report hair loss, but that's obviously pretty uncommon or you'd be reading about it everywhere. Your red blood cell counts can go high and some men report their PSA climbs or they have enlarged prostate. These can occur with any testosterone therapy.
The sides that you'll mostly read about with injections are when they let estradiol get too high. This can happen because injections do a nice job of increasing your testosterone.