S&P2 is a great game, it really is. But I'm not as crazy about it as other people here are.
You've watched the trailer on the e-shop, so you have a pretty good idea about it. It is a straight up action game from beginning to end with almost no time to rest. Every second is more intense than the one before, and the game really doesn't forgive your mistakes. You play on-rails but you have control over your character's movement anywhere on screen, but you should stay on the ground to gather more points (it's more difficult to evade this way though) you will also be using the Wiimote to aim at the enemies or creatures you want to shoot. At any given time you can fire constant shots by holding B, charge shot by holding A (which takes a few seconds to cool down), or tap B to perform a melee strike. you can also use the melee attack to counter some enemy projectiles and throw it straight in their faces. So with all these options you are constantly engaged in shooting, charging, evading, and deflecting attacks through swarms of enemies until you clear a level. And thankfully the level design is just as good as the core mechanics of the game.
There are 7 (or maybe 8? i don't remember well) levels in the game. Each have their own theme, enemies, and rhythm. And yes, they are very creative, very intense, and over all fantastic. The boss fights in this game are outstanding as well, I dare say some of the best I've experienced on the Wii. So although the entire game is around 4 hours long. You will feel the need to get right back into the level again and again until you mastered every nook and cranny of the game. Personally, this is the "great" part of the game. The reward for mastery isn't some unique weapon or points or upgrades or any of that shit. No no, mastering the game gives an intrinsic feeling of achievement as you realize that the levels have a certain flow to them, and getting in that zone is the point of this game.
HOWEVER, what bogs the experience down for me are two things.
First is the animation, it needs to be said that the game has great animation overall, but I don't like the fact that the characters don't react to their surroundings, or should I say react very poorly. The sense of speed isn't reflected on them, the explosions doesn't seem to bother them, the water or sand all seem to be treated similarly, etc. etc. It gives a feeling that the characters are in some kind of green screen, completely detached from the experience. Of course you will be too busy worrying about what's going on the scene to care, but to me it really bogged down what could've be an absolute masterpiece.
Second one is the sound design. Yes the game has a suitable soundtrack, but my god are the sound effects terrible. They just don't feel like they give the extra oomph to accompany the visuals.
So yeah that's my complete opinion on S&P2, I recommend it, but I don't think it's a masterpiece.