If you are a Disney fan and even a Final Fantasy fan, then Kingdom Hearts is the game series for you. You travel to various Disney worlds, and Donald and Goofy are your sidekicks throughout the game (only in KH1, KH2, and KH3). Also, Mickey Mouse is known as the King in these games.
2002 was the year that the first Kingdom Hearts game came out, and to this day, there are about 12 games in the franchise, with the 13th one (being Kingdom Hearts 3) coming out this year. Now you're probably wondering, "That doesn't sound right, the 13th game is being released this year and it's only titled as the 3rd one??" Well, the numbered ones are the "main ones" in the series, while the other releases are "side stories", which are just as important and as essential to play as the numbered ones.
The Kingdom Hearts series is a very complex one, but it is so much fun. Traveling to the different Disney worlds and living out the stories as depicted just like they are in their movies, it truly is amazing. Within these worlds, there are challenges and enemies called "Heartless", "Nobodies", "Unversed", or "Dream Eaters".
You are fighting for peace from the enemies in these worlds, and ultimately you battle against the Disney world's antagonist as the final boss in these worlds. It is a lot of fun to explore these Disney worlds and live out the stories that are just like in the movies.
The overall story and plot is truly amazing, though. It is super complex and sometimes a bit difficult to follow, but once you play it all and read all about it, it is easy to follow. This series is very unique, and it is one of those series that you just have to try out for yourself. Having a fellow friend such as I to explain it to you, would take days to understand, and you would get a headache if someone were to explain it to you. Verbally, it is hard to understand, but playing the games (or watching videos on YouTube and/or reading about the series) would help out a lot.
Otherwise, whether you would play it just to experience the Disney aspect of it, by all means, go for it. It is a very fun series regardless you follow the story or not. It really is worth it, and I would play in release order if I were you. Get your hands on a PS4 and buy the HD packs of these games (KH1.5+2.5 and KH2.8), and patiently wait among the millions of us for the release of Kingdom Hearts 3.