While I've never owned one myself, I have fished out of a friend's Ranger (whatever their fish-n-ski model is called). It's a Ranger, so very nice boat and he obviously had the same general pros/cons that Micah stated (the happy wife and kids was a biggie). However, I noticed a couple of additional cons that, as a bass boat owner, I would not be happy with (keep in mind I do not have a wife/kids to keep happy):
Windshield - while a windshield is very nice during cold weather, I felt that it sometimes got in the way when casting.
Front/Back Deck - I'm sure there's a nautical term for this but, where the hull rises above the front and rear fishing platforms is very high on fish/ski boats. Obviously because they have to pull double duty as a sitting area, but I mean around twice as high as would be seen on the highest true bass boat, upwards of 8"-12". This made things a little difficult when pitching/flipping as well as when working a topwater or jerkbait.
Also, the shallow access is diminished somewhat. These are just some of my observations from fishing out of a fish/ski and the concept lends itself towards some compromises. As the old saying goes, happy wife = happy life, so these cons are probably a small price to pay in the long run.