Up until five or six months ago I'd never played a Kingdom Hearts game but I'm glad Sony made a bundle of the two previous main games plus the other side games available, with the ability to play the previous games before the release of Kingdom Hearts III.
That said, this game is by far the most gorgeous in the series (no surprise given that this was made for this generation of consoles) and the audio is spot on. Combat is great and, compared to the other games, there seems to be a natural evolution to it when it comes to special attacks. There are a lot of side games/activities that seem to fit naturally into the game. Probably the best way to say it, is that everything that was good about the series is big and better in this game.
As for the story, it is both a highlight and a lowlight. In its own way it's good because there's so much depth and you can tell the developers put a lot of work into it. On the other hand, this means that the game gets bogged down in cut scenes as they try to tell the story of each individual world and then deal with the overarching story of the main heroes and villains. It isn't too noticeable or annoying in the first couple of worlds but by the time you reach "Frozen" and "Pirates of the Caribbean" it becomes tiresome. Part of me appreciates the attention to detail and wanting to give as much a summary of the movies each world showcases but at the same time, doing nothing more than watch cut scenes for ten plus minutes without a chance to do anything but is annoying. Plus with the game trying to tie up almost every lose end from the other games in the series, I kind of wish they'd found a way to do it in a more concise way.
I highly recommend this game but would advise that anyone playing it not try to start the beginning or end of any particular world if they've got limited time. You need to be able to be prepared to sit for a while until you're able to get to a save point.