model is a nice finger exercise for more advanced models. Ending up with stationary perfect foresight [sic] equilibria in which log[GDP] follows a random walk with drift isn't too exiting. The innovation process is Poisson and that's it. So all this human capital related stuff like learning, imitation, et cetera isn't incorporated. The only interesting thing is that the laissez-faire growth rate can be larger than the growth rate under a social planner. Though obvious empirically, you wouldn't expect that from a theoretical model.. ;-D.