These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Batgirl 2000
Base Breaker: She's either awesome, or an overrated Mary Sue. As seen below.
Ensemble Darkhorse: She got her own series. That says as much. Similarly, frequent guest star Spoiler gained quite a following.
Replacement Scrappy: Cass received this at first, and still runs into it from time to time. Due to her popularity, it also lead to Steph getting this when she became the new Batgirl.
It's not just that she's being compared to Barbara. It's also that she replaced the mysterious Batgirl who was introduced earlier in Batman: No Man's Land. The reveal of that Batgirl as Huntress and her sudden loss of the costume to Cassandra was very abrupt.