Oh, but at these ages age can most definitely be a problem.
They are at different psychological stages in development at these ages.
At the age of 16, one is still dealing with psychological stages associated with sexual maturation. This is when the teen typically begins to ask and find out "Who am I?" This is also when the adolescent is acquiring a sense of identity essential for making adult decisions such what they want to do with their lives. During this stage in life there are also new social demands, opportunities, and conflicts that one must overcome.
Now, the age of 25 is when the young adult has ALREADY developed a sense of identity. This is when one is able to fully participate in the community, enjoying adult freedom and responsibility.
These two particular ages are so far apart that it rarely, if ever, works. They are striving for different goals and have different responsibilities.
Now, if you are talking about a 30 year old and a 39 year old (same age difference, different psychosocial structure) it can work beautifully.
Psychologically we mature at different speeds. The mental, emotional, and psychological ability of a 16 year old is nowhere near that of a 25 year old.
The above is not my opinion, but research done by Erikson (a famous developmental psychologist). The below, however, is my opinion.
I still maintain that this borders on pedophelia. Why would a 25 year old want to date someone as young as 16?