I'm only about four hours in, but I figured I'd post my impressions in hopes of getting some other folks to pick it up. When I went out to get it, I really didn't have any idea how it worked, so I'll try to explain it for those people who don't know what it is.
I guess the Mystery Dungeon genre/games are all like this - it's like a real-time turn-based role-playing game. You move around dungeons, and each action you take represents your turn, whether it's using an item, moving, or attacking. But, to be honest, I didn't even realize this until five or six minutes into my first dungeon. I was just button mashing and seemed to be doing alright. If you hold the start (or select? can't remember) button, you can see the actual tiles that you move around on. This adds a lot of strategy to the game, since some of the enemies can be pretty tough. Speaking of enemies, they're all Pokemon (of course) and everyone has movesets from the games, with moves like Quick Attack, Growl, Thundershock and such. In fact, it's pretty similar to the rest of the franchise, in that you can get poisoned, burned, paralyzed, and there are items to heal each of these things. The items are the berries from the games (Oran, Rawst, Pecha, etc.), which is pretty cool, I think.
You start out with two team members (yourself and another), but eventually you get the option to add more. I think every time you fight an enemy in a dungeon, it adds "respect" to a meter and the more respect you have with a Pokemon, then the more likely the next one you fight is likely to join your team. I was in the middle of a battle with a Starly and he asked to join my team. Then, we just walked off together, with him in tow. I'm not sure how many characters at once you can have exploring with you.
You can assign "tactics" to your individual team members; basically, "wait here," "stay next to me," "attack on sight," "avoid first hit, but assist," and stuff like that. You can also assign which moves you want each team member to use. Like, before a big fight, I'll tell my teammate to only use his best move, but while we're wandering around a dungeon, I'll leave a wider variety of choices for him, so that he doesn't deplete the PP of his best moves. Four moves per character, just like in the rest of the franchise.
You have a basic attack that doesn't take any PP (yes, there's PP, just like in the games), but you also have your moves. You can hotkey a move, so that, to use it, you hold down L+A (A is your normal attack).
You level just like in the other games - defeat enough enemies, gain enough experience, and you'll level up (and your partners, too, at their own rate). When you level, your attack, defense, etc. goes up, and you learn new moves.
Also, there is a stat called "belly." I'm not sure of its purpose, but I know that it starts out at 100 and depletes as you move around a dungeon. Eventually, a pop-up will inform you that you are "woozy from hunger" or something like that. Items exist that "fill your belly." Certain items will also raise your IQ (which is separate from attack/defense, etc. Not sure of its purpose, either) in addition to filling your belly.
The dungeons are, like advertised, randomly generated, so that every time you enter a dungeon, it's different. This is cool, because most of the time, if you're trying to get through a dungeon quickly, the staircase to the next floor (dungeons are split into floors) will often spawn really close to you. You won't have to travel through the entire floor to reach it. Items and enemies spawn randomly, also. Enemies will continue to spawn even when you're just doing circles on the same floor, or when you wait.
So, when you hold down A+B, you can wait. Or maybe it's called rest? Anyway, you continually gain back health as you're walking around, so waiting is useful for regaining it back fast. Basically, you're just bypassing your "turn," even when you're not battling. So, while waiting, everything goes really quickly. Enemies will spawn and enter your area, at which point you can just let go of A+B and plan your attack. Although, typically, I'll just let my partner handle them while continuing to hold A+B.
If either you or your partner runs out of HP, you get teleported out of the dungeon and back to your home base, and you lose most of your money and items. Maybe all of your money, I'm not sure. There is an item bank and a money bank where you can store stuff safely before departing on a mission.
Missions are picked from two categories - normal missions (like retrieving items or delivering items) and outlaw missions, which are basically simplified boss battles. You recieve items, money, and explorer points for completing missions. Explorer points rank you up, but I'm not sure what that entails, yet.
Overall, it is pretty fun, mainly due to the rewards. Getting money and buying items is always fun in games, and so is learning new moves. And it was a pretty cool feeling adding a new member to my team. Also, the game can get pretty tough, which is a welcome change from most Nintendo games. I've died three or four times and had to restart a dungeon. With a limited inventory (which increases as you level), you have to be sure to have the items you need with you. Sometimes, enemies are pretty tough and they'll do, like, 3/4ths of your HP in one hit, so you have to alternate turns between letting your partner/you attack, and using items to keep the two (or more) of you alive.
I haven't done any of the online stuff yet (trading teams, rescuing others, downloading dungeons).
can't wait to hear it from all of you guys.