Super Mario Galaxy is a game that manages to elicit pure joy, with rare nose dives into painful frustration.
To just get it out of the way right now, the story is basically non-existent. This is typical Mario story telling at it's most pure and simplistic. Peach got snagged by Bowser and now he wants to rule everything. Mario must save her. There are some other story elements added involving another blonde damsel, but for the most part these elements can basically be ignored.
The gameplay is an amazing mix of elements from all past Mario games, with additional original ideas added in as well. There are 3D "flat" levels, just like in Mario64. There are side scrolling 2D levels, just like in the NES/SNES Mario games. And, there are plenty of 3D upside-down "planet" levels as commonly seen in trailers for this game. All of these types of gameplay are present, and they are all done extremely well on a ridiculously huge variety of levels.
The power ups available are also all done in a very clever way. Power mushrooms make a return, but in a pretty cool way. Normally you get 3 hitpoints that are displayed in a circle on the upper right corner of the screen. Collecting coins refills one hit point up to a max of three. However, the power mushrooms push you up to a total of 6 hitpoints. Once you go back down to 3 hitpoints you loose the bonus and your max available returns to 3. It really makes finding those Power Mushrooms before a boss encounter quite helpful.
Most of the other power ups are on timers, such as invincibility, flower-power (throwing fireballs), ice-Mario (walking on water by freezing it). However there are plenty that stick around until you cause them to go away. The Bumble-Bee and Spring suits stick around until you loose a hitpoint or touch the water. The power ups are all very creative and add quite a bit of variety just by themselves. The only one that becomes even slightly frustrating would be the Spring suit simply because it can be a bit annoying to control.
The game progresses through the collecting of a total of 120 stars. As you collect more, you get the ability to unlock more levels, which in turn provides more opportunity to collect more stars. The odd decision to require only 60 stars to "complete" the final boss encounter involving the story line was a bit of a surprise as it leave you with the feeling that you have only played through half the game. Having set this number up to 80 or 90 would have seemed to make more sense. Fortunately you are not forced into the last encounter at 60 stars and can go around finishing as many levels as you want up to 104 stars before starting up the last encounter. Strangely, the last 15 stars do not become available until after Bowser is down.
There are several rooms that you can enter, which each have a System in them containing a handful of Galaxies. Each Galaxy that you unlock has multiple star challenges available. When you select the Galaxy you pick which star you want to attempt to collect, and the level path is then specific to that challenge. The advantage here is that one Galaxy can have up to 7 stars on it, but each star challenge will have you playing that Galaxy in totally different ways. The end result is a lot of variety between star challenges that are all on the same Galaxy.
Each Galaxy also has plenty of secret star challenges. Using the term "secret" here very lightly, because the game will basically tell you that there is a secret star on a specific level. There are also extra challenges that show in the way of comets. These are probably some of the more difficult ones throughout the game. They often entail racing against a shadowy version of Mario, or completing a boss encounter with only 1 life point.
Eventually you will get to the last Galaxy within each room. This is usually where a major boss encounter happens that adds a little bit to the story. These encounters are quite fun, but seem to be all very similar. Even the mini-bosses that are scattered around various Galaxies tend to be a bit too similar with each other. This is not a very big deal since as the game progresses there are more layers of difficulty added on to each boss encounter, but it is a little bit of a downer. Overall the boss encounters really are a blast to play and become quite memorable. They are challenging, but not "smack-your-face-with-a-wiimote" challenging. Which is good because you might hurt your wiimote had they been that hard.
All of this does not mean the game doesn't have problems. There are a few issues that are present which range from slightly odd to downright WTF?. The minor odd issues are forgivable, and might not ever be noticed by most players, but the WTF? issues are glaring.
The worst parts of Mario Galaxy are easily going to be a handful of the Star Challenges that appear to be completely and painfully out of place. Most of the gameplay is fairly easy, yet still enjoyable. However there are a few challenges that are beyond frustrating. There are 2 particular challenges that require you to throw bombs at piles of trash to blow up all the trash within 30 seconds or so. These are a total waste of time and just flat out do not belong in this game. They are not fun at all. Period. Zero entertainment value. Even picking up the star once you complete them feels cheap. After you complete the final Bowser level you unlock "purple comet" challenges. Most of these range from easy to challenging while remaining fun. Some of them are absolutely the single most difficult parts of the game, bordering on impossible. For someone such as myself that is crazy Obsessive Compulsive, this is just not acceptable. I can't help but shake my head in wonder as to why these few insanely difficult challenges made it into the game. The main reason for there difficulty is strictly due to the control style. For every other level in the game the controls work perfectly fine. But these few frustrating levels require a level of precision that is just not tuned in with the controls. Having the game suddenly become an exercise in control frustration was definitely a major let down. I collected 116 stars before giving up and was left with slightly bitter taste in my mouth for an otherwise incredible experience.
Overall Mario is really the first game anyone should consider when they purchase a Wii. It is easily the best game on the platform, and also one of the best games to come out for the entire year across all available platforms. The astounding amount of fun and enjoyment available are well worth the price, and easily makes up for the bore-fest that was Super Mario Sunshine.