Quite possibly the best game on the N64, Banjo-Kazooie offers plenty of challenges and fun.
Even though it does not have a lot of replay value, Banjo-Kazooie is one of the few games I have played more than once. The dialogue and gameplay are extremely intelligent. This game does not disappoint -- with clever level design and outstanding characters, it offers plenty of challenges and fun. Gameplay is akin to Super Mario 64 and Rayman 2 -- both wonderful platformers in their own rights.
One thing Banjo-Kazooie brought to the table was the clever dialogue; it did not take itself too seriously. There in lies why Banjo-Kazooie managed to rise above its contemporaries -- it was sincere and humorous.
If you have never played the N64 version, I urge you to purchase the X360 version (you know, if you have an X360). You will not regret the decision.