Had DC been serious about making her Robin I think she would have been a breakout character instead of the niche character she became as Batgirl. The idea of a girl being Robin in-continuity would have been huge, much bigger than being Batgirl #3. Big missed opportunity for DC, but that's what happens with a pigheaded and stupid editorial.
Morrison would say she was really Robin. Didio would say she wasn't. In the end it doesn't really matter. She should have been, but DC was more interested in Bat-dick and shock-deaths than character development or branching out.