Its really good, if you can understand the Brit sense of humour.
Also, you have to overlook the big anti-hunting theme. I mean, the WHOLE movie is about how hunting is bad and evil. The hunter character, Victor Quartermain, is a buffoonish, arrogant, violent, evil man that spends his whole time trying to kill poor, sweet, innocent, fluffy, plauge rabits.
If you can get past that, its pretty good.