I have been playing Spore this weekend. I liked the other Maxis games (well, besides the Sims), so I tried this.
On Amazon there are 1700+ people who are complaining about the DRM and are refusing to buy the game. (I don't know why Amazon lets people review a product that hasn't even come out yet, or a product that the person hasn't bought through Amazon). Overall, the setup and online registration is no different than a MMORPG. The game uploads and shares your creature creations, so it is not much different at all.
The first phase is the Cell phase, floating around in the primordial ooze. I like this phase the best. Nice ambient music, and graphics that look as if you are looking at this in a microscope, with different layers of the slide out of focus. Nice touch.
After you harvest some parts from other creatures, you can "evolve" your creature. You do a mating call, another creature like you shows up and does a mating dance and the program goes into Creature Creator mode.
At higher levels in the Cell stage, it becomes a "cell eat cell" world, and I was dying alot (luckily dying doesn't take anything away from you). I found that the best way to survive is to make a hideous creature with flagella, fins, two mouths, and spikes for protection.
Ater climbing out of the ooze, I enter the Creature stage. I added legs and changed my creature to what is seen above.
When you get to higher levels of the creature stage, you need to form a pack. This requires making allies with your nest mates or other creatures. You do this by imitating them in a "Simon says" way, by singing, dancing, posing, or charming (the four green buttons). This is a lot like many MMORPG's. Whether you can do these things and at what level of effectiveness is dependent on what body parts that you add to your creature. That is why I added a bunch of crazy stuff to this earlier creature, like horns, and wings, and nubs, as seen below:
Overall, I like this game. It has good game design and it is a casual, relaxing game, especially the Cell stage, which I like the best. The biggest issue that I have is that the game and game controls completely change between Cell, Creature, and Tribal level. It took me some getting used to the Tribal level, because the camera and control buttons changed drastically.
The game comes with stand-alone Creature, Tribe, Civilization creators where you can save your creations and share them with the world. I haven't tried these in great depth, but they are very fully featured and detailed, almost in an over the top sort of way.