This was the first Kingdom Hearts game I have played and, admittedly, perhaps I should have started with the first game. Story elements aside though, the gameplay is terrible, controls feel unresponsive and the level design is boring. It works in a complete mission and then return to base type way which for the first few missions is fine, but when there are multiple missions per 'day' and you need to return to base four times, it seems a little OTT and unnecessary. Simple enemies take forever to defeat, which means boss fights take even longer, leading to boring and repetitive button mashing.
It isn't all bad however, the characters were fun and interesting and the story progression for the five hours I played was good too which kept me engaged in the narrative.
This bad experience hasn't put me off the series forever as I think I may start with Kingdom Hearts 1 on PS2 and see if that plays any better. This is a side game anyway and so probably isn't totally integral to the story. I am just a little shocked as I haven't seen anyone say a bad word about this series and with this being my first experience playing the series, this game is bad.