OK... I am a huge Harvest Moon fan, and this new offering is a decent addition to the franchise.
The best parts? You finally get to whack creatures with a sword. The cooking makes more sense, since you have to work up skills to create more difficult dishes. Forging is great! It takes mastery, too, which I appreciated. Befriending monsters is interesting and helpful. Finally there's a decent replacement for the sprites. Plus, they are not as tedious to take care as other animals. The dialog with the townspeople is a lot more interesting this time around.
The average parts? Farming is about the same, although there is less of it to do. Collection is the same as the rest of the games (although there is less of it since you only collect in caves and on your land).
The worst parts? Earning money and enough wood at the beginning is tedious. There's only one house upgrade. You eventually have way too much dough. Creating accessories is not as balanced as pharmacy and forging. Cave traveling is redundant. The festivals aren't as fun as in previous incarnations.
At first I almost stopped playing this game, the beginning is very very slow. But once you get past that it turns into a very cool mix of the normal harvest moon sim fun we all have come to love and enjoy with the fantasy sort of rpgish side added it, which gives it more play value and replay. It's definitely not a game that you will get through in a few hours though, so be prepared for the long hawl!