Extremely fun! Just did a 100% playthrough on hard mode and had a great time. Some of my favorite boss fights in games, gorgeous environments and cinematics, and the best combat in any Metroid make me very forgiving towards the kind of silly story and the more restrictive exploration (which at least still feels more free and open than Fusion.) Also, if you're a freak for shinespark puzzles and precise platforming, you will love 100%ing this.