I got hot flashes after a week on T injections (I also got that monthly thang after a week on T). Then the hot flashes went away for about a month, but have started up again this past week. Incidentally, that monthly thing should be happening now-ish (but it hasn't happened, so woot) and I wonder if the hot flashes are related...
And yeah, what other people have mentioned: hungry, scratchy throat, more energetic, sleeping patterns thrown outta whack (happened when I was a teenager as well), libido was slightly higher (but nowhere near as unmanageable as when I was 13).