Essentially, Billy Madison is gauged for a pre-teen to teen audience, a group which still enjoys fart jokes but doesn't demand R-rated ones to get their laugh on. It is also a film which plays better when the audience is familiar with Sandler and his Saturday Night Live characters. One isn't quite sure during the film whether they're laughing with Sandler, at Sandler, or at any audience that finds the film funny, but one will laugh.
In terms of the video and audio quality of the Blu-ray release, no one is going to be blown away. There really isn't anything wrong with the visuals—there is no dirt or scratches present, black levels are good, and some of the scenes in Madison's backyard are quite pretty—but there is really nothing that is going to make anyone stand up and shout about how great it looks and how much detail is present. The 5.1 channel DTS-HD Master Audio track is also free from defects, and the surrounds are used a little in terms of setting a scene, but there is no equivalent of an eye-popping moment. The audio track is a delivery line for the jokes (the ones that aren't visual) and the excellent soundtrack but little more than that.
The selection of bonus features is relatively paltry. There is a feature commentary from Davis (one that isn't new to this edition), deleted scenes, and outtakes. Yes, there are a whole lot of deleted scenes (more than 25 minutes worth), but as with most deleted scenes there's unquestionably a reason why these were removed from the final film.
In the end, you certainly won't be any dumber for having watched Billy Madison and you probably also won't lose anyone's respect for having thought it funny from time to time. Adam Sandler can be a truly funny comedian and shines at moments in this film, but it unquestionably isn't his best work. Fans of his or of SNL and SNL films will get the most enjoyment from Billy Madison, but most folks will find a thing or two to smile at.