Good presentaion, with minor flaws, but seriously FUN (WARNING: Long but detailed Review)
Let's get the early problem out of the way. A lot of people mentioned the difficulty of the first boss fight (Eikoku / Eigen) at the Suzaku Temple. It took me about 5 tries to beat him, and it was really frustrating, but I realized each time I was defeated, that if I just tweaked the strategy a little bit, he wasn't hard at all, and each time I got closer to victory. Needless to say defeating him was VERY satisfying, and that satisfication has held through ever since.
Here's my laydown of that fight (WARNING: YOU MIGHT HAVE MORE FUN IF YOU FIGURE THIS OUT YOURSELF)
if Eigen rushes you with a long genbu combo, hold the O button to break his combos, and if you're low on health, run away and prepare Chi attacks (square). If you just broke his combo, you could also counter with your own combo. The annoying part of this battle is that his combos are long and you can't heal while your juggled (obviously). Also, he'll trash talk you as soon as you get knocked down, during which he is invincible. Use that time to get away and charge up Chi. Blast him with Chi. Rinse and repeat.
END SEMI-BOSS-FIGHT-SPOILER
Although the first boss fight was sorta frustrating, it does teach you practically everything you need to know to survive this game. Parrying is extremely useful later on, and the fact that enemies can break your combos without you being invincible certainly helps the balance of the game. I will point out that Chi attacks are a bit skewed in your favor (but later bosses use them too, it's no walk in the park). Also some large semi-bosses will juggle you as well, so the difficulty can be challenging, but how is a game fun if it offers no challenge? Contrary to what's been said, it's NOT all button mashing, you have to aim your hits by knowing your kenpu's strike zone / range, and also, you have to know when to stop a combo and switch to other combos for maximum effectiveness. There is some latent caching of you button presses, so if you mash O three times, you'll do 3 moves of that combo even if you switched bugei or stopped pressing.
The story is mildly predictable, but it's still decently fun, and the world, though relatively small, offers lots of lush scenery and room for exploration. The graphics are certainly the best I've seen on the PSP, and the music is great. But all that's been said. Now, about the voice acting.
They seriously butchered the Chinese / Japanese names and dialogue. Though the average American gamer wouldn't care, seeing that I've studied both languages, it was really irksome (Byakko is a major ouch, it's NOT BYE-AH-KO, it's Bya-KO 2 syllables). I did enjoy the Asian mythology and eastern theme to the game though, but that may just be me.
Overall, if you're into an martial arts or liked God of War / Ninja Gaiden, Kingdom of Heaven is probably the closest equivalent to those games on the PSP.