It depends on how you define "good." If you're just looking at it purely as an action RPG, each installment ranges from poor to solid in that aspect, and I wouldn't recommend it. The characters in 3, Frontier, and Tides of Destiny are fun, but not really great, and the storylines are fairly simple. What makes the series stand out is how well they married the life sim gameplay of Harvest Moon to the action RPG gameplay. You get up in the morning, work the fields, tend your monster companions/livestock, maybe chat with some townspeople, and then head off to a dungeon to kill things with your wife. That's what makes the games fun.