I can't say how the Lowrance charts compare with Garmin, but I find the harbor detail to be fine. It is as good as the small scale harbor charts. Also, Lowrance periodically puts complete software updates on their site that updates the charts. I was also able to add MARPA to my radar by simply downloading the upgrade. I am quite satisfied with my HDS system. That said, for my second boat I am going to go with a netbook running SeaClear II, at least until I decide that I definitely need radar.