In my opinion this is TMI from him --especially at the first session. Saying he is in therapy to normalize it and assure you that he's doing/done his own work is totally appropriate. Getting into what his issues are and the fact that he's on medication strikes me as excessive sharing so early on. What I find concerning is not that he has issues but that he feels the need to tell you about them. He should be demonstrating that he gets what his clients are saying/feeling mainly by doing all that good listening, validating, and asking questions stuff that good therapists do. He should not accomplish this by opening up and telling you how much his life is like yours--or at least not often and not right away.