Trixie has come a good ways in the course of the show (both shows actually… some of the more rounded work with her appeared in the "Forgotten Friendship" EQG special), and I'm glad that she's still popping up even this many seasons after her wagon first pulled into Ponyville. I've always enjoyed this type of character… the brash, egomaniacal type who often brings about their own comeuppance (or simply suffers indignities at the hands of a less-than-sympathetic universe.) I always find myself rooting for them, even as I enjoy their setbacks.
I hold out hope that, with the rumored final season of the show coming next year, we'll have a chance to revisit the Twilgiht/Trixie dynamic. I love their interactions… there's a great, antagonistic chemistry there that just hasn't been mined as successfully by pairing her against/with Rainbow Dash, Sunset or Starlight. Here's hoping the two original unicorn mages get to butt heads one last time and perhaps come to some kind of final understanding of each other before the last episode falls.