Is Mrs. Thatcher irrelevant in modern politics?

I remember when I mentioned I didn't praise Mrs. thatcher, this Conservative guy wouldn't accept my opinion and challenged me, saying "If Thatcher failed, why was she re-elected?". I also remember my university lecturer saying Mrs. Thatcher is an "obnoxious woman", which I wouldn't really agree with. Myself, I've always thought Thatcher is a bit of a lightweight, about half as intellectual as she thinks she is, and no more of a brilliant leader than say, Disraeli, Churchill or Heath, she is not exactly my hero.