Bad Boys 1 and 2 were great. they were both so authentic. The chemistry between Mike and Marcus was amazing. the stories were great. both were hilarious without trying to be funny every 5 seconds. part 3 was bad, part 4 was even worse. You can tell Martin Lawrence hasn't acted in a long time, Marcus was a dork in 1 and 2, but in 4 he evolved into a clown who complained and tried to be funny about everything. Another actress played Marcus's wife, which further took away from the movie. The story was stale and did not flow. Rush Hour 3 and 4 suffered from the same things.
this review comes from a huge Will Smith fan, the dude fell off big time.