I actually liked Police Academy 3 better than the 2nd one. They're back at the academy and the original recruits are training the new guys in a competition to save the academy.
The characters play the same types of pranks as in the first film. The addition of Zed and Sweetchuck into the academy is entertaining, if you can put up with Bob Goldthwait that long.
Overall, I wouldn't rent it but might watch it for awhile if it's on tv some sunday afternoon.