The series ran three seasons of differing lengths. The basic story is about a family of three, Rick, Holly and Will Marshall, that get flung into some kind of place that has dinosaurs and creatures called Sleestaks. They have to find a way to try and survive and also try to find a way to escape the Land of the Lost.
The first season is fairly decent; the second season is the best, in my opinion, and the third season is awful. The third season saw the departure of the actor playing their father, so their "uncle" shows up immediately and takes over the role of parent-figure.
Most of the special effects are very cheesy by today's standards, but were decent for when the series was actually made. The show fails to deal with the biggest questions of all, and that is what created the Land of the Lost, since things there work under the control of crystal matrices in pylons and do not necessarily obey the laws of physics.