I'd always heard really good things about this game but never tried it. Yesterday was rainy, I was bored, so I picked up a copy.
I'm really impressed with the game. Side by side, this game is better than Metroid. Metroid, having come first, gets the nod for creating the genre but this game really takes everything Metroid accomplished and turned it up to 11.
The music is creepy sci-fi perfect for this type of game. My home theater subwoofers really get a workout when I play.
The difficulty is at what I would consider a perfect level. You die, a lot, but it's not controller throwing hard. There's usually a save point really close to where you'll probably die, a lot, that really cuts down on the frustration. I figured this out after moving from save point to boss battle through about a dozen rooms for 10 - 12 times then realized there was a room just to the left I'd not explored. The 13th trip to this boss I decided to hang a left just to see what was there... The doors to the boss's rooms are red too, so if you see one of those and haven't found a save point look left!
The weapons are awesome and it seems like there's going to be a ton. In about 30 minutes of just getting into the game I'd expanded my health two or three times, found two tools that could be used as weapons, found two more main weapons, and increased damage once or twice.
The story is the polarizing point. The premace seems cool but I was so eager to get into the game I wound up skipping through. I later went back and watched and found it meh. Metroid had the right idea here. There were 6 pages in the instruction manual explaining what was going on. When you turned on the game, you got a few seconds of intro music and were off. Some people said the story was great, others thought the characters were forgettable and story underdeveloped. One way or the other, it doesn't detract from the game, at least for me.
Any metroid fan should have this game. It's an obvious homage from an adoring fan.