Fixes everything 3 had wrong and delivers awesomeness.
One of the coolest aspects of P3 returns this time around. The social links. By spending time with and making friends around town you develope social links. These help improve the persona you can make in the velvet room (the place where you can fuse persona to make more powerful ones). Each individual you befriend has an arcana from the tarot deck you can strengthen through your time with them. Since each persona is influenced by the arcana who you spend time with strengthens different persona. Most of these social interactions are hilarious, heartfelt, depressing, sad or just fun. But always entertaining. You'll often find yourself not wanting to go level up and instead just spending time with a friend just to see what happens next.
COmbat has been drastically improved from the last game. Thankfully you have full control of all your party members this time around. You can choose to have the computer control them instead, but anyone who played 3 knows this is a horrible idea thanks to very poor ally AI. Otherwise combat is much the same as 3. Different persona have different strengths and weaknesses, so if you're on a dungeon floor with lots of fire enemies, you don't want a heavy ice based party for example. Thankfully dungeon design has been greatly improved as well, You no longer grind through one dungeon the whole game. You get several based on people's inner thoughts. Kanji's is particularly hilarious, but they're all interesting. The dungeon floors are still randomly generated however, so if you're not a fan of random dungeons this will be a negative for you.
There's so much more I could tell you about this great game, but that would take too long. I'll just add in that this is a very long game. I put in nearly 80 hours and could have added at least another 10 or so if I were more diligent with completing everything. The story does get a little thin at the very end and there's a way to finish the game with one of the lousy endings depending on your choices at a certain part of the game. This will likely tick off quite a few people when you finally confront the killer and all of a sudden the game ends abruptly with no real explanation of why things are the way they are, but rest assured you have at least another 10 hours or so of game left at this point, you just have to choose differently. SO always make a backup save file so you don't save yourself into a corner. There I think I managed to add my warning without any real spoilers. Besides this the story is one of the most fun and engaging I've played in a long time. Characters are well done and like-able, the twisted mystery stays intriguing throughout, even the music conveys an appropriate (if sometimes odd) vibe to help the story along. It's only at the very end when you confront the final boss that things get a little thin in the story department. SO anyway, great game, awesome story, lengthy quest and all around fun make this a must play for any PS2 role playing fan.