I played the first KH, and it was a confusing soul/love-fest clusterforget. The storyline of "Hey let's find these people before they die... OOOH WHAT'S THAT! LET'S GO OVER THERE!" was just handicapped and I lost interest in it fairly fast. The combat was ok, but again if you play a game simply for the action then you might as well get God of War instead. But really, the main reason I stuck to it longer then I should have was the Gummi-ship stages. It sounds gay (and it is kind of), but you could make your own ship out of blocks and stuff and I had made a giant Cube with a forget load of lasers tucked in it and drove it through solid objects and all kinds of crap wrecking everything. Maybe I was just very bored because that feature probably wasn't all that great either. Then I hit that loving Water-World place and finally gave up.
I saw my sis play the second one and it just seemed like the first one, except more confusing and pointless and with more button mashing and farming.