This has nothing to do with the character, but I'd hold off on more character discussions for at least a week. Checking the wiki shows there's almost 100+ characters, so no need to crowd them all together. I liked Trish's idea of a "character of the week", but maybe it doesn't matter.
Back to what does matter: Brown Sugar. My, oh my, what a sexy character. Whereas Marcy is sexy without trying to be, Brown Sugar knows she's got a rockin' body and has no qualms about flaunting it. Her costume is tight, skimpy, and emphasizes all her best assets. She also had my favorite robo-girl outfit, and I agree that her slave collar really pushed her up and over the edge in the sexy mind control department.
A few other things I like about her; for starters she's actually got a rather conservative set of morals. Despite her obviously sexy get-up and raw beauty, she's got high standards when it comes to relationships and she's even a bit religious, which is a vast and satisfying contrast to when she inevitably gets mind controlled and becomes an uninhibited sex slave to some fiendish villain.
I like how she’s one of the most mature and experienced heroines as well. Whenever she’s around, even if she loses, she always acts like she’s in control of the situation and never lets her emotions get the best of her, which even more “veteran” heroines like Ms. Metrobay and Omega Woman are prone to doing sometimes. Many younger heroines have expressed outright respect and admiration for Brown Sugar, especially since she’s taught most of them first-hand. She’s almost a mama bear type figure for many of them, and I find it hot when she lets out the claws from time to time.
Now for some things I feel need improved. For starters, she exists almost entirely as Brown Sugar. When she was introduced she was just as captivating as civilian Caramel Georgia Brown. That side of her has all but been lost, which is unfortunate since I think that’s actually her BEST side. As a heroine, she’s great, resourceful, and sexy, but as Ms. Brown we can see the social side of her that other heroines, such as Alpha Woman and Ms. Metrobay, routinely enjoy because they have no secret identities. I’d love to see what she does during her downtime. Is she still undercover at APEX? Does she date socially? Does she struggle to hide her dual lifestyles? And does she indeed produce chocolate milk?

As Trish mentioned, she also has a very interesting history (one that I myself might hope to leave a little imprint on), and I’d love to see more of it. Like Batman, who trained all over the world, she’s got global experience that makes her sort of a cultural melting pot. She’s adaptable and can adjust to almost any environment. She’s an ex-spy and that’s another side of her we don’t see often, not since her introduction. Tapping into what she’s good at, which is the whole espionage and infiltration bit, would be great. Disguises, gadgets, the whole secret agent bit. She’s a one-woman Charlie’s Angels and that could probably be played up a bit more.
Other than that, she’s a great character. She’s overcome her status as a stock character, or “token ethnic heroine” and stands proud as an individual with compelling potential. I would love to see some fresh ideas with her, especially considering just how versatile and adaptable she is.