Oh the problems this thing had:
1.) The plot was too complicated for what they were trying to do. It was an interesting story, but couldn't be properly told without dialog, and it was shown from too many viewpoints.
2.) That said, out of ALL the scenes, the ONE that they had to cut was the intro that explains everything. Metaknight's ship gets stolen, Dedede tries to help, etc. They couldn't have just cut one of the many stupid filler scenes? It's pretty ****ing embarrassing when the developer has to come out and apologize for the story not making sense, then posting the official interpretation.
3.) The levels boiled down to a bland beat-em-up. That gets painfully stale after about 8 hours. The levels felt the same in terms of play and there wasn't much to do but fight.
4.) Legit tho, the most complicated puzzle design they could think of was: "Durr the green key unlocks the green door!" Seriously wtf
5.) What is your reward for 100% completion? NOTHING. ****ing Sakurai came out and said "Well isn't the feeling of 'doing it' an achievement enough?". No, it isn't. What's the point to strive for completion if there's no incentive?
See, adventure mode worked because it was short, and offered enough variation in what the player actually had to do. I won't miss SSE.