I didn't try Luminous arc yet (I think the screen is too small for a Tactical RPG. that was the case with Hoshigami in my opinion)
I'm playing and enjoying Rune factory.
It's the first Harvest moon I'm playing a lot, it's good the get an RPG and Exp system with it.
The game looks nice. You will make exp in cave a lot I think, but it's ok. It will let you see each season, and maybe 2 or 3 game's years before end game.
I'm waiting for Rune Factory 2. it might be even better.
For the gameplay :
The stylus is almost not needed in this game. only sometime in the menu.
You will have to work in your field at the start of the game (clean up, and start growing seeds and fruits to sell them).
Speak to everyone often to get every tools to help you in your adventure, and befriend with them to let the game story running.
In each cave the climate remains the same. one cave is always spring, another always summer etc.
It helps to keep seed growing all the year.
The Purpose of the game is to marry one girl and live with her at least 1 year.
edit : and of course finish the story by killing all the cave's boss.
Each girl will have different needs to be able to ask her for wedding.
http://www.fogu.com/hm/rune_factory/
A very good site with all the help you can need.