I would say she is neither mean nor nice, I think she is a product of her environment and has little original thoughts of her own - raised as a pure blood, and I think once she married Lucius, she adopted his beleifs as her own. I believe she was in full support of Voldemort's manifesto in the early days of his power, however whether or not she fully supported the extremes that he goes to, I'm not so sure. A part of me things that she beleives his methods to be far to extreme, but she has no courage to back out, she goes with the majority to keep herself, and her son safe - she only ran from voldemort and his regime, once she was safe from his wrath.
...all in all, i think she is more cowardly than anything else.