She has a fairy tale bimbo personality that doesn't really fit the game setting. I could also do without vanilla interiors being littered with unsuitable collectible toys (maybe it'll be all right in shops or houses with other toys around, but mostly they are out of place).
Gameplay-wise though she surpasses any other NV companion, original or not, which is even more impressive considering mod's release date. Much needed combat options, complicated bonding / reputation system, lots of companions and locations comments (and option to turn them off), quests being unlocked after months of in-game time, separate inventory for player's stuff and a lot more.
Everything is also consistently written and well scripted without any serious bugs.