I have owned my O'Neill neoprene drysuit for 6 years and I love it. I will buy another when this one dies. I think they are the best bang for the buck.
What year is it? What is she asking for it? You can buy a brand new one for $500. When I bought mine 6 years ago it was $750. Add about $150 for brand new thermals.
I replaced my zipper after the 5th year. The zipper replacement was $160 as I recall.
They fit well (assuming you get the right size), very streamlined, warm, no problems for me with the seals or valves, etc.
Fire away with any questions. I dive mine year round. Last weekend we had 39 degrees in Gloucester. I added dry gloves last year.
--Matt