If you are familiar with other games from NIS, you'll recognize the brand of humor and animation from the Disgaea franchise. It's a got Prinnies (including your starter wife), anime-style references, and the whole plotline is a boss-fight. Please note, this is a rogue-like game and not a tactical RPG.
Yep, you are in a boss fight. You keep losing until you win, as the story progresses, and you become more of a hero. It's amusing and over-the-top.
The actual game is fun for until you get around chapter eight on the storyline. At that point, you can't just keep going in dungeons blindly and bash, because your shadowgram is full and completing a dungeon won't appreciably raise your stats. This a rogue-like with endurance (if you run out of food, you starve). Whenever you complete a dungeon, die, or turn off the PSP mid-dungeon for that matter, you lose all the stuff you are carrying and your level resets to one. Your stats may get boosted a little based on your combined total levels.
Now the game lets you have some work-arounds. You can unlock buildings which have various abilities, and purchase special devices for your shadowgram. They let you carry more stuff, save items, and lose less energy. If like me, you don't have an Energy Saver by the later game, (a random drop from the caravan mid-dungeons), you'll will really suffer in terms of endurance. Ideally, you want an Energy Saver + a highly forged Appetite Engine to minimize endurance loss (oh, and absolutely don't dual wield unless it's a straight-forward boss fight... you'll starve).
While I have been enjoying the game, parts of the grind became annoying, especially having to constantly redo early levels to farm meat against later board starvation. My advice to completionists is deliberately run out of money early, so your wife makes you the 'bad lunch', otherwise it will be agony to get it. The other big thing I missed at first was when forging items together, you can use the L/R buttons to switch to your inventories. That way you can forge more than the two weapons you can equip.
If you like rogue-like games such as the Mystery Dungeons and the Tower of Druaga, you'll like this. It is on the easier side for a rogue-like though, meaning the gathering-type repetition is not interesting. At least that's my take (and why I only rated 3 stars on fun).