I like her in small doses. But everything about her in the 90s anime is loud. Her color scheme, her voice, her attitude. She's a brat in R, even though she has her reasoning. But I think her part to play in R was one of the few times she really wasn't redundant. There she has a plot, a motive, and a part to play in the finale...both in the manga and anime.
I think bringing her back for Infinity/S was overall detrimental. She did have a plot with Hotaru, which was sweet, but again, this was a tad redundant since Usagi or one of the other girls could have filled this part pretty easily. The plot was already so Usagi/Mamo focused that Chibi Usa just pulled away more screentime from the others.
They could have fixed her by actually giving her some training episodes in S and unique attacks and things to do. Besides the Hotaru stuff, she is basically pointless in S and I almost wish they'd left her out in the anime version. I had a younger cousin who was "Rini" obsessed and it was cute. I liked that Chibi Usa inspired her, so I get the appeal for younger kids.
I will say, the idea of Queen Usagi sending her back to be with her younger self to find friends is sweet...and also weird since shouldn't she be finding friends in her own time? All of these kids she's meeting will be dead or 1000-year-old adults back in her own time.
In SuperS and Dream, she's definitely given more plot...I guess. But I don't really like it. The manga is fine...but I feel like Chibi Usa's presence dumbed things down. Especially in the anime. I thought the Pegasus scenes were some of the prettiest but I just can't get into it. It's weird, it's creepy and it's kind of boring after it drags out so long in the anime.
I like how we see her mature and begin to kind of develop her own thing, but again, she is redundant. She's just like her name, a Little Usagi and I'd rather we'd have explored Usagi and Mamo deeper or especially the other girls. Chibi Usa gets to ring a bell in the anime or mirror her mom in every way in the manga, right down to having color-coded guardians with little to no personality.
But even after all of that she really gets cheated in both versions of Stars. Especially the anime. I become full-on indignant about how they treated her there. We are supposed to get behind her having her own anime series during SuperS...she goes back to playing side character in the Nehellenia arc (I like her here) of Stars and then she's just gone with no send-off episode, no closure to her arc and she doesn't even get to come back in the end of the anime. Absolutely trashy how they handled her. She should have had a send-off right before Mamoru left. I know it's mentioned and that the manga does this similarly, but after giving us three seasons/arcs of Chibi Usa, she did deserve better. Her return in the manga isn't a lot better. It feels so forced and shoehorned in.