DS2 is very polarizing. Miyazaki didn't work directly on it and personally it is my least favorite. However it is still a phenomenal game and I wouldn't recommend you skip it. It has the best weapon and armor variety and introduced an incredible dual wield mechanic called power stancing. The DLCs each have really brutal sections so I wouldn't hesitate to coop them if you don't want the challenge. The biggest issues (imo) with it are that the world isn't built at all as cohesively as the first dark souls and that there are lots of ganks (enemies randomly attacking you from hidden places or far away). Also the bosses are not quite as diverse as other dark souls games.