This is my take on the situation
To me, Transgenders should be allowed to serve in the military.
HOWEVER
They should not be treated any differently than regular members of the military. They should be able to act in a professional, dignified manner and be able to put aside their personal issues to do their duty in the military in a professional manner. If they need HRT or Gender Reassignment Surgery, they should get that stuff done before they enter.
In the end, Transgender or Not, they should be able to perform to peak capacity as soldiers because loveual orientation is irrelevant when it comes to serving in combat operations
This is just my opinion though. In the grand scheme of things, I'll defer to the presidents judgement on this.