Persona 4, the only real fault about the game is that it ends eventually.
Persona 4 starts out pretty much like Persona 3. You play as the protagonist, whom you name, who is on his way to the small, rural town of Inaba. He is going there to live with his uncle for a year while his parents are overseas on a business trip. On his way there, however, he is sucked into the Velvet Room, where he meets Igor and Margaret. There he learns of the trials and hardships that will eventually cross his path during his time in Inaba. They aren't given out in detail, obviously, but he is left with those few words and is flung back out into the real world. In Inaba, there has been a gruesome murder of a TV announcer, and a mysterious fog has been covering the area for some time. All these mysterious get revealed, but you must figure out what is causing the murders and the source of the fog.
The way the game progresses is pretty much the same as Persona 3 as well. You play each day out and move on to the next and so on. Each day is broken up into sections: Early Morning, Morning, Lunchtime, Afternoon, After School, Evening, and Late Night. Some days events may occur in the Early Morning, like a friend coming up to talk to you, or nothing may happen. It all depends on what day it is. You always have After School and Evening to choose what you want to do, though. Also, like in Persona 3, you can join clubs and build your Social Links during these times. If you didn't like how Persona 3 played out, then why would you play Persona 4? But if you're willing to try something different, then Persona 4 is about as different from a traditional JRPG as you can get.
Depending on how the weather is, your friends may be out so you can talk to them and build your Social Links, or you can take on certain challenges that you can only do during certain weather conditions, like the Chinese Diner Aiya's "Rainy Day Bowl Challenge".
However, one difference from Persona 3 is that you now have Part-Time jobs you can take which can earn you money and increase certain areas of the protagonist's personality. There are 5 different parts of the protagonist's personality that you can improve: Courage, Diligence, Understandings, Knowledge, and Expression. Each of these are required to take on certain Part-Time jobs, and they also allow you to do better in school, ask a girl out, or make you more popular. Certain Part-Time jobs only open up after certain points in the game, and require a bit more from the protagonist's personality traits, but some of them are worth. If it means money, or items you get because of the job.
The battle system is also pretty much like Persona 3, but now you can manually control your allies! So you won't have to deal with the frustration of having your allies not heal who you wanted them to heal, or use an attack that they shouldn't use against a particular enemy. It's still far easier to just give them a certain Tactic to use and let the AI control them, but for boss fights in particular, you may want to control your comrades so they don't make a stupid mistake. It's still fast paced, fun, and often very goofy at times, in a good way. There aren't many games that feature an attack called, "Galactic Punt" which never gets boring to watch.
Fusing Persona you obtain is also just as interesting and sometimes confusing as in Persona 3 as well. One big difference in the fusion, though, is the new Fusion Forecast, which displays certain bonuses that the Persona will get if you Fuse some together on a certain date. This way, you can plan to get even stronger Persona by fusing them on certain days, which can allow you to plan your calendar more accordingly. You of course have your Normal Fusion (Fusing 2 Persona), Triangle Fusion (Fusing 3 Persona), and eventually you unlock Fusions up to 6 Persona. Trying to fuse more than three Persona require certain ones to make these more powerful Persona. They can be a hassle to obtain, but they are really worth it compared to the others you make through Normal or Triangle Fusion. You still have your Persona Compendium, which stores all the Persona you have obtained. You can summon them again for a fee that you must pay to Margaret in the Velvet Room. This is very handy if you're trying to make those uber Persona.
The very anime inspired graphics may be a bit of an eye sore for those who are used to current gen RPGs, but this is on the PS2. So what do you expect? For the system it's on, the graphics are very crisp and nice to look at, though they are VERY Japanese, as this is a very Japanese style game. The Persona and characters are very distinguished from each other and they each have their own spark of life thanks to the style of the game. The animated cutscenes are, of course, very well done and put in during important parts of the game. So they're not around single corner, so you shouldn't get overwhelmed by them.
The music is hit or miss. If you liked Persona 3's quarky and off-beat soundtrack, then you'll enjoy Persona 4's. If you didn't...then you may want to play the game on mute and listen to some of your own music. But for those who enjoy the music, you'll want to obtain the OST ASAP. There are some memorable and catchy tunes in Persona 4. The voice acting is top notch. Each voice fits their character well and you most definitely won't want to mute this game due to voice acting. If only every RPG had the kind of voice acting Persona 4 has.
There are multiple endings to Persona 4, which you can obtain on the first playthrough, so you don't HAVE to play through it a second time. There is a bonus dungeon that you can only go into on the second playthrough, though. The way the ending is determined can be kind of annoying, as they're determined by a series of questions at a certain point in the game. If you know how to answer the questions, then you're fine. If you don't, then you'll want to check Gamefaqs or a guide to see how to get past that part. You can carry over some stats (money, Persona Compendium, and some other things) to your second playthrough, but not much.
Overall, Persona 4 is a must for those who loved Persona 3, or for those who just want something different from an RPG. If you go into it with an open mind, you'll find one of the most enjoyable RPG experiences out there. The aspect of Persona 4 that separates it from the crowd isn't so much the heavy Japanese influence in the game, but how the characters are so well defined. And by the time you're done, you'll feel like you've said to goodbye to some true friends.