Gotta be gameplay, if the controls are cumbersome and progressing in it is difficult not because its hard but because it was made poorly I can't enjoy it. Even if the characters and story and atmosphere and everything is great, if the GAMING aspect is bad, its a bad game. If you can't get that down, make it into a movie or a book and leave the programming to people who know what they are doing.
Otherwise it would be like reading a book where the pages are covered in thorns, might be a good book but after a while you're just gonna say fuck it, I'll read the synopsis on wikipedia.