Not sure whether Henins decision right or a knee-jerk reaction.Personally i feel it is early as she is only 25.
Any other profession (ENG,MED,Software etc.)you can do at any age,but sports you can do only between 17-32.So unless there is severe injury top class sportsmen should not retire below age of 30.Aggassi was 37,Pete 33,Lance Amrmstrong won couple of Tour de France after 30 and that too as a CANCER SURVIVOR.
High pressure should not be a reason for any person (sportsman or others) to quit.As Bille Jean King said PRESSURE IS A PRIVILEGE FOR CHAMPIONS,HEROES,WINNERS!!!!!!