Hum Tum is basically a story of a cartoonist who believes that men are from mars and women are from venus. The movie moves around karan kapoor played by saif who is a cool guy who loves flirting...and he has got his own views on women and for that matter on life.
So he tries to understand a pretty young thing, Rhea played by rani and they fool each other and karans humour is really fresh. Things move well till Saif kisses rani and rani sees red and they move apart and then meet after a gap and then separate and then meet again separate again and then...
Saif comes back in a solo performance as a funny flirt guy role after quite a gap, and he is refreshing
all in all it is a worth watching movie. Check it out at least for saifs views on women at least.