Aside from the change of method of controlling, the rest of the game is no different than any other game in the series.
To begin with, you may feel frustrated as you get used to the idea of only using the stylus. There are mixed feeling about this around the Internet in the gaming world for this game. Some say it spoils the gameplay and makes the entire game impossible to play, others will say it makes no difference at all and once you've learnt how to use it, the game itself is very playable and very enjoyable.
In Harvest Moon: Island of Happiness you don't have to be social if you don't want to but if you want to fall in love and get married then this is something you would need to do, obviously. Each girl has their own desires and you would need to figure this out if you want to get on with them.