Luminous Arc is a good game for "Tactics" fans that has a pretty good story and online capability.
Story
The story is pretty simple and predictable at times but it is pretty decent. It's about a band of orphans led by a Knight to slay witches and monsters. There are a couple of twists here and there but nothing you can't predict if you follow the story. Overall the story is ok that has a little bit of humor to it.
Gameplay
The gameplay for Luminous Arc is pretty standard for an SRPG. You take turns walking around a map and slay enemies. There isn't really anything that distinguishes Luminous Arc from any other SRPG. There are a few things that Luminous Arc has that differ from other games but nothing special. There is something called a Flash Drive in the game. Think of it as a special move that each character has. There is also something called a synergy drive. They are specials that two characters perform when their FP bar (special's bar) is full and they are near each other. Unfortunately I haven't really found the need for the synergy drive because it takes a while to perform it and by then you might have already beat the map. There is also something about the gameplay that I dislike. There are a couple of minor instances of lag during the game. This doesn't really affect the game too much because it doesn't happen that often. There is one level, however, that have major lag but other than that it's not that bad.
Music / Voices
The music is pretty decent. It gets a little repetitive if you played as many hours as I have but isn't terrible to listen to. The one piece of music I really liked was the opening song to the game. This game features voice acting. Not for every single dialog of the game but a pretty decent amount of it is voice acting with text boxes to show what they said. The voice acting wasn't horrible but it could've been better. Some of the voices are pretty good and has the right emotion to make it believable. There are, however, some bad voice acting in there, whether it sounds like a robot or it is just plain annoying. I think that the voice acting wasn't really necessary but wasn't too bad to listen to at times.
Difficulty
The difficulty of the game is pretty easy. It doesn't really offer that much of a challenge besides a few levels and the optional 20 level (I think) tower/ruin you get to play in after you beat the game. The game requires you to level up at some times (because of stronger enemies) but the leveling system can be abused in this game. The lowest amount of EXP you can from killing a monster is 6 EXP. You need 100 EXP to level up. However, whenever you use a stat boosting move on another character (other than yourself) or if you heal another character you get 30 EXP. Almost all the characters have at least one move to do that so it can bring your characters at a high level pretty fast.
Others
There is online capability for this game. I have yet to play it online so I can't really tell you how it is. I can imagine it adds some replay value to the game when you are done with it. There is something called intermissions in this game. What it does is it lets the main protagonist (Alph) talk to one of his comrades after the battle. This isn't necessary to for you to understand the story but it is a fun feature that sometimes lets you know more about the characters.
Conclusion
Overall I think this is a fairly decent game to play as long as you don't have high expectations for this game thinking it is going to be like other SRPG games like the Fire Emblem series or Final Fantasy Tactics.