Spore
On account of the fact that I couldn't really remember much of what I did when I played it initially, I decided to start again (my new race was a crazy bird creature with all the primary colours coated on it) - it turns out that, with the possible exception of the last one, the five phases don't take very long to plough through. Technically, I'm not completely done, but I've exerted enough dominance over the galaxy to feel like it's done.
Firstly, the elephant in the room, the Creature Creator. It's clearly one of the most impressive character creation tools ever to grace videogames and perhaps always will be, but to be frank, I found it intimidating. Just the pages and pages of creature parts were a bit daunting, and then you see that you can meticulously scale segments of limbs, rotate features every which way, adjust the torso down to each individual vertebra... aaah. Based upon the number of YouTube videos out there of stuff made in Spore, there are many people who obviously enjoy just messing about in the creator. For me, there's too much to get a handle on, plus there's the creative bankruptcy getting in the way. Moreover, at the end of the day, what your creature looks like does not make that much of an affect; certain pieces carry attribute boosters, yet I didn't really pay attention to this and did just fine.
As for the phases of gameplay, the quality oscillates. The Cell phase, whilst occasionally strategic in how you deal with bigger organisms and featuring a neat depth-of-field effect, is essentially glorified Fishy, which is one of the simplest Flash games out there. The Creature phase starts to introduce more of the Sims-style mechanics and is more involved, although I found the controls to be somewhat awkward at times.
Reviews generally agreed that the two real-time strategy phases were very stripped down, and yeah, even as someone who's a relative RTS novice, I can tell that the Tribal phase is really basic. On the other hand, the Civilisation phase is a considerable upgrade on Tribal -- nowhere close to its namesake, the Civilisation series, but closer to the level of complexity I would want from this genre. However, this phase does require a lot more use of the creator to make your buildings, tanks, planes and boats. Again, for some people that might be great news. If you aren't adept at using the toolset and have no imagination, like me, it is not great to have so much to construct in this phase.
Finally, the Space phase is by far the longest of the phases, though not always for the best of reasons. It's fun to terraform planets on a whim and I enjoyed the subtle references to The Hitch Hiker's Guide to the Galaxy. However, it hits upon an issue that is pervasive throughout every phase: Spore is a very easygoing game. In the slower-paced Space phase, this can make proceedings wear thin after a while.
Whether or not somebody would like Spore is dependent on what they expect to get out of the Creature Creator. It's incredibly robust and comprehensive, perhaps to a fault. The actual game is always straightforward, but some phases are better than others.