I would not hesitate to buy an O'day again as we were quite happy for a number of years on our 32. As to construction, I'd say they are VERY SLIGHTY better than the Hunt/Bene's of that era and had more livable space which made them very nice weekender boats. Sailing performance suffered a bit as a result but they still performed decently and since we are not racers, had no problems in that regard.
The big issue with these boats today of couse is that they are orphans and finding specific parts like overhead lighting etc. is difficult. Otherwise, they face the same issues of wear, care, blisters, moisture ingress, etc. as similar boats of the same era and a survey is mandated.