You will either Love it or Hate it
First thing is first, the hype of this game was basically second to the second coming of Jesus, and guess what, it's not Jesus, but it's a very good game if you look at it for what it is, not for what you thought it was.
Considering that the game is broken into 5 pieces, which you have undoubtably read about by now so I won't go in depth on them.
The big thing to take into consideration is that no of the 5 stages are as advanced or as complex as the benchmark games of those types. For example it is true that the Tribal stage is an RTS, but only on the most basic of levels, if you're looking for the next Starcraft, go play Starcraft, this is not it. Same can be said with the Civilization part. Don't let the name fool you, it is as far removed from Civilization 4 as you can get.
But here is the key thing, just becasue they are simple doesn't make them bad. The point of Spore isn't about beating those stages, they are designed so that you will beat those stages. The challenge is in how much you want to challenge yourself. For example if you love to play as a military power, you'll steamroll the computer in no time, but if you try to do it in a playstyle that isn't your instinct then you'll have a little bit more of a challenge.
But why should I change my playstyle for the game? Becasue it's not really a game as much as it's a toy and the end goal of it is to create YOUR galaxy and YOUR empire the way you see fit. And that is where the game becomes a cousin of "The Sims" in that you're creating your game as you go. And getting back to playstyles, you change them because of how you want to play once you get to space to give you different bonuses.
So is this game/toy for you? That really depends on what you are looking for. If you like to buy a game and rush to the end making sure to beat it, then this probably isn't a game for you, it's just not that hardcore by any means. If you want something that you can play with and tinker with in a more casual way with some gameplay elements then this will probably delight you.
Additionally there is a lot of complaints that the game is too shallow. Personally I have to agree and disagree all at the same time. It's shallow in that there aren't a million different skills and techs, and other stuff to find/build. But it's deep when you start to look at the interconnectivity of all of the elements. For example the first time I reached space I thought that I'd basically build my empire and start to roll over other empires at my leasure. After getting routed back to my home planet I reassed my gameplan. The second time into space I made friends with all of the races around me and this gave me time to build without having to deal with constant attacks (many on the forums complain about the constant attacks, done right you can avoid them).
It's a game that can be a lot of fun and it's a very different style of RTS (if you could even call it that). My advice read up on the critic reviews as this game appears to be very polarizing in that people either Love it or Hate it, there isn't a lot of middle ground. As for me, I'm loving it.