Thank goodness the writers were able to give her some strong character and development, otherwise she would have been useless fluff.
Also... I think she looked a lot better in Starfleet uniform (reference the episode "Relativity") than in a catsuit. In fact,... ALL catsuit-wearing Star Trek characters looked better in uniform. Troi, Kira, and especially T'Pol
Not to mention that Jeri Ryan was a capable actress and able to carry the weight of the episodes focusing on her.
It sucks that it was clear from the start that the primary purpose for her character was T&A, though...