I'll give you an honest review.
The game's all about going through randomly-generated dungeons and doing missions, with a story about how you're a human who's been turned into a Pokémon. There's a personality quiz that you take at the beginning, and depending on how you answer the questions and which gender you choose, you'll become one of sixteen different Pokémon. You can then choose a partner from one of ten Pokémon (or less if the Poké you became is a Fire, Water, Grass, or Electric type), who will accompany you throughout the whole story until the credits roll.
Gameplay: The core gameplay consists of taking rescue jobs, usually consisting of "Rescue this Poké", "Escort me to this Poké", "Bring me this item", or "Find this item in the dungeon". The escorting job can be the most annoying depending on the dungeon, as the Poké you're escorting is usually pathetically weak and easily taken down in one or two hits. There are also some event-related things that I won't spoil for you.
You can recruit Pokémon for your team in the game. Most of the time it's a simple matter of owning their friend area (which you can usually buy or get in a mission), being a higher level than them, and beating the crap out of them, making sure that your leader is the one who strikes the fainting blow. You can have a team up to four Pokés with a max body size of six, but the majority of the dungeons in the game let you only bring a party of three Pokés, saving the fourth slot for any potential Poké friends or escorts. There is no breeding, shinies, or a Pokédex in the game, though, so don't bother looking for them.
Anyway, on to the random dungeon design. The dungeons basically consist of rectangular rooms connected by a series of hallways and are filled with random enemies out of some pre-determined ones for the floor, random items, wonder tiles, traps, and staircases leading to the next level. In other words, it's no Diablo......but you weren't expecting that from a Poké random dungeon game, were you? =P
As for the battle system you can do regular attacks or learn moves. The basic rules for Pokémon battles apply except that every time you move one step in the dungeon, use an item, or attack, every ally/enemy follows up with their turn, doing one of those things. You can also link moves together in town or with an item, so you can use two, three, or four moves in a single turn.
In my opinion, the battles and dungeons can be fun at first, but can get very repetitive after continuous play. You move, your partners move, your foes move. The type advantages and disadvantages make things a little more interesting, but there's not that much difference as in other games because now moves that used to not even hurt a Poké just do very little damage to it. Also, when you're introduced to traps later in the game, the dungeons will start to really **** you off when you step on a tile that drops you to a lower floor or get all the PP drained from your precious Flamethrower or Hyper Beam attacks. There is also a hunger meter and unseen time limit for the floors that I haven't mentioned that encourage you to just find the staircase ASAP instead of spending too much time trying to catch that Mr. Mime you want for its precious Recycle ability that lets you recycle used TMs. =/
Graphics: I was very impressed with the sheer number of Pokémon sprites in this game. There are sprites for all 386 Pokémon, including all the varieties of Unown and all the Deoxys forms. There are even multiple sprites for left and right poses with asymmetrical Pokés, so Absol's horn/ear is always on the right side of its head and Roselia's always got a red rose on its right arm and a blue rose on its left arm. The only real flaw in the graphics is the unimpressive dungeon designs.....but there's not much you can do when your dungeons are of the "rectangular rooms with hallways" type.
Sound: I think the music for events in the game is pretty good, but the dungeon themes can get repetitive. The sounds for special moves are just decent. The sound does get extra points for not including those Game Boy era Poké cries that we're all sick of by now, though. =P
Overall: I'd only recommend this game if you really like Pokémon and the Mysterious Dungeon games (like Torneko: The Last Hope and Chocobo's Mysterious Dungeon on Playstation). If you like both of those (and I do), then the game gets an 8/10. Subtract three points if you don't like Mysterious Dungeon. ;P
Final Score: 8/10 (if you liked Torneko or CMD)