I haven't taken Celexa specifically, but I've taken 3 different anti-depressants over the years before finding one that really that works for me. I don't believe any anti-depressant is inherently better than the others, but each works slightly differently and sometimes it takes some experimenting to find one that is right for you. No one else can say ahead of time whether it will be beneficial. However, side effects to anti-depressants tend to be mild. If your daughter has any negative changes in behavior or her physical health after starting to take the medication, report it to her doctor. Effects are temporary, so even if it doesn't work out, it will leave her system and she can try something different.
How old is your daughter? There has been some concern over the years of negative effects of SSRI's in teens, and I don't know much about how they would be prescribed to younger kids. This is something you would have to discuss with her pediatrician, though.