I'm fine with Trys. She's a different kind of character from the Vulcans and half-Vulcans we've seen on Star Trek; she connects more to her human side. Considering TV Star Trek's bizarre biological determinism, that's progress. She also serves another role: she's a young officer who can be mentored by Picard. Everyone from TNG is too grown up to need that kind of relationship. I don't see much similarity with Abby, though. Trys is young and learning, whereas Abby is heading into middle age and seems arbitrarily quirky for the sake of having at least one dimension to her personality.