My rating is based on my opinion of the first four or five seasons. The show starts, as many shows do, better than it finishes up, but the first few seasons are excellent. Patrick Warburton is the stand-out here, and his reparte with David Spade is the reason I tuned into the show in the first place. They both do their absolute best from the first episode to the last.
The younger couple... well, mixed reviews from me. They were more entertaining early on, but then Jen got kind of a superiority complex, and Adam went from naive to just plain stupid. Maybe that justifies Jen's constant eye-rolling, but it's not fun to watch. There are also several episodes later on that appear to have been written with the sole requirement "find a reason to put Oliver Hudson in Spandex".
Supporting characters who were brought in during the series' run are of two basic types: outstanding (Timmy) and blah (everyone else). Timmy infused the show with new vitality and served as a very clever and entertaining foil for Spade's character of Russell Dunbar. The others (Timmy's thankfully brief office girlfriend, and the gear-grinding Liz) didn't fit in and didn't add enough to justify being there.
All in all, I'd recommend it to those who enjoy sitcoms. It's cleverly written and the performances by Warburton and Spade are excellent from start to finish.