CD is absolutely right, the hair you have transplant will remain but that around it will fall out with time without drug intervention (I wouldn't recommend the drug intervention, I hear from a friend it has some screwy side effects

).
Therefore, unless you were totally bald at the time of the transplant, as time goes on its not going to look right, and you'll need further procedures to 'fill in the gaps'.
My hair loss is starting to become more advanced, and should I feel the inclination I am not ruling out a transplant down the line, but its not a priority and would have to be when I am out of the woods totally with regard to the PFS side effects, and certainly when I am done with pro-hormones as they make you shed like a motherbitch. Pro hormones are an important cornerstone of my recovery, so its not something I'm giving much thought at all to right now.