I've heard of Etrian Odyssey, but I've never really looked into the series. What's it about?

Its a hardcore dungeon crawler RPG with random turned based battles. Battles are in a first person perspective with static enemy sprites for that old school feel.
What makes this game unique is that you have to draw out your own map of the floors, and super enemies called F.O.Es patrol these floors. Every step you take, they take one, or two. They may have set patterns, or they may chase after you to no end if they see you. Worse still, when you're in a battle, after every turn they still move on the map. Its not a great idea at all to take on an F.O.E the moment you first see one. The game is very unforgiving as it is. Even the labyrinth itself can screw you over:

"You see a fruit growing from a vine. It looks tempting, why not try one?"
>Sure
"You take a bite and instantly feel nauseous..."
*Lead member loses 50HP*

"There's a flower field. Rest here?"
>What could go wrong?
*Enemy ambush*
Venomous butterflies poison you for 25 damage each turn. It's the beginning of the game...... you have 30HP.... you can't flee...

In short, it's an awesome series but it might be hard to get into because of its brutal difficulty. The beginning is the worst. You start off weak, very, VERY, weak. Monsters can and WILL kick your party's ass left and right. You need to put a lot of time and effort to the game, but when you do it feels very rewarding. It'll feel satisfying to take on those F.O.Es once you're ready and get their rare drops.

All 3 Etrian Odyssey's are for the DS. I recommend starting with the second one, it's basically an upgraded version of the first, however its the hardest in the series in my opinion. The third game introduces a new set of classes and the ability to subclass and it's a bit easier to get into, so if you'd like you can skip the first two and start with the third.

The fourth game is to be released for the 3DS early next year. I highly recommend playing the series if you're dedicated to these kinds of RPG's.

Mm, sounds like a pretty strategic game. Thank you, that was very informative-- it definitely sounds like it's worth checking out. The music's good, too. :)

Yeah, it's really fun experimenting with different party formations.
You're welcome, I was a afraid it was too long-winded. ^^
Unfortunately the music I linked is an arranged version of one of the game's tracks, so it won't sound like that in game, but the real music is still awesome, especially the normal battle themes. :D