There are 5 main planets, with one planet only being visted at the end of the game (I won't spoil anything.), and if you want to include it, there is an abandoned spaceship.
But yes, I must say I found the game spectacular on every front. The graphics were trulyt breath-taking. I sometimes would find myself pausing for minutes on end just to look around at the environment. The controls are very fluid, The voices detract in no way from the overall feel of the game, the music had a nice feel to it, and I didn't want to stop playing it overall. This game is a must-have, if you have to purchase a Wii simply for this, it is more than worth it.
I give it a 9.75/10. It was a spectacular game, however in a place or two the music felt slightly awkward. I wouldn't necessarily say this is the end-all of Metroid games, but it is without a doubt one of the best.
However, I'm curious as to what you consider a "Gamer's game", APERSON. Could you explain further?