I've spent about 2 hours in the game so far (just finished the first floor). My impressions:
Visuals and music are both great for a DS game.
Difficulty level has been hard enough as to require several trips back to town, but not hard enough to be overly frustrating. This is with my Survivalist, Dark Hunter, Troubador, Medic, Alchemist party. So far, I've had two characters die on me.
Enemies don't drop gold. Instead they drop body parts which can be sold back at town or used to complete quests. Selling items back at town often results in new items in the shops depending on what item you sell.
The skill system works like this: each character has the same number of skills available to them although which skills varies depending on the class. You start out with 3 skill points and gain an additional skill point each LV-up. LVing up a skill requires 1 point regardless of level. Also apparently you get a few extra skill points if you retire a high level character and start a new character. Skills often have skill prerequisites (1 or 2 specific skills at certain levels of proficiency), but no LV requirements. Pressing A on an unlocked skill tells you what skills are needed to unlock it. I believe LV10 is the max for individual skills. Skills seem to fall under the following characters:
Magic/Technique Skills - Your standard "Spend TP for an effect" skill.
Permanent stat Boosts - seems like all class have HP & TP Up and some classes have additional stat boost skills (like Agi Up for the Survivalist).
Passive Skills - some examples would include the Medic's ability to heal a small amount of health to all party members automatically without spending TP at the end of each battle or the Troubador's skill to increase the rate that XP is gained.
Harvesting Skills - there are 3 of these and they can be used at specific locations in the dungeon to harvest items. Increasing the skill LV increases the # of times per day (game days, not realtime) they can be used. Very important. The Survivalist has access to all 3 of the skills whereas most classes have access to 1.
Proficiency Skills - These are passive skills that are mainly used to unlock new skills although they often also boost the power of skills in their tree. Examples would be the Survivalist Bow skill and the Alchemist's Fire Up skill.
My opinion of the classes I've used so far:
Survivalist - Bow fighter with some nice support skills like a passive skill that increases the rate of pre-emptive attacks and a spell that boosts party speed. Fast with decent damage. The harvesting skills look like they'll come in handy as well.
Troubador - Average fighter with tons of support spells. They have spells to boost most statistics, restore HP or TP gradually per turn, add elemental damage to weapons, increase resistance to a certain element while decreasing resistance in the enemy, and so on. The aforementioned XP boosting passive ability looks like their ultimate ability (in my book anyway). Looks like a class that'll start out slow, but could end up very useful at high levels after they've unlocked some of the more powerful abilities.
Dark Hunter - Warrior with special attacks that boost damage and add negative effects. There are two sets of techinques; one set for whips and one set for swords. Not sure about this class just yet, but the early poison whip technique does very nice damage when it hits and the poison does a surprisingly large amount of damage per turn as well (about as much as the attack did in the first place).
Medic - As expected, this is your class with a ton of healing techniques. Pretty much what you would expect from such a class although I did notice a high level physical attack technique called Caduceus that costs a good chunk of TP and has a stun effect added to it which might make a combat oriented Medic worth trying out.
Alchemist - Specializes in fire, ice, thunder, and poison magic. Also has a couple of miscellaneous spells for outside combat. So far, her basic Fire spell is 1-hit killing everything.
Miscellaneous battle information:
Anyone can fight, regardless of which row they're on although it looks like there's a penalty for attacks from the back row. I believe bow attacks are exempt from this penalty.
Each character has a Boost command which is basically a limit break that boosts the power of their next move. The Dark Hunter has a skill that increases the effectiveness of Boost.
I think I'm going to enjoy this game a lot. The two hours I played went by quickly. The combination of exploration, map drawing (gotta love being able to quickly enter in notes via the touch screen keyboard), combat, and character planning looks like it's going to make for many fun hours.