When that outer shell is removed, his true nature shows through and it is hilarious. Liar Liar is a big step for Carrey as an actor. His love for his son looks genuine. Carrey is not a great actor, but he's not bad when called upon. I hope Carrey is able to follow up with more great comedy like this.
Good comedies are hard to come by.
Just check your local video store and prove it to yourself. All the great films are docudramas, action epics, or space sagas. Comedies come and go and are often forgotten as soon as the credits roll. It's hard to sustain the humor for two hours and leave the audience calling for more. Jim Carrey has that gift and it was put to excellent use in Liar Liar .