It has an awfully slow beginning, but it picks up pace later. It's in my top 10 games of all time, and I think the best endorsement I could give it is that all the little things that nagged at me early like the gibberish speech and somewhat Issun, became absolutely endearing by the end of the game, to the point that one of the cutscenes during the final boss fight always manages to bring a tear to my eye whenever I rewatch it. It's a game that is vastly rewarding to stick with to the end, more then any other lengthy game I played.
If you can't take the art style though, imo the best in all of gaming, then I don't know if there's any helping you. People like to dismiss the game as just being loved for it's art which is far from the truth, but any game I hated the art style of I wouldn't want to play for 40-60 hours. Maybe it'll grow on you, but that's all I can offer. It's soundtrack is excellent, it's characters endearing, it's story a great mix of humorous and bittersweet, it's gameplay with the brush fairly unique and provides a nice variety with your standard attacks.
I have no issue calling it one of the greatest games of all time. To me it's not style over substance, it's style is substance.
It also has the best final boss theme of all time :