The plot is great because...
...Eddie Murphy's biggest problem is that he cannot be quiet. He always has to babble around. In films like "Beverly Hills Cop", "Coming to America", "Dr. Dolittle" or "Life" this was quite amusing (because they were actually good films), but lately he was really annoying in stupid movies.
So the idea that he only can speak 1000 words is not a bad one. :-P