Statistically, you like Grand Theft Auto. Being totally upfront, while I've owned every game in the series released thus far at one point or another, I've never really devoted significant time to them. This isn't for lack of enjoyment, but due to a few nagging issues I have with the gameplay of the series itself, Rockstar's approach to making games in general, and a wealth of other games that have a far more apparent appeal to me. That said, there are certain things the Grand Theft Auto games do exceptionally well.
Here's a list of what I love about the GTA series, as well as a list of what I don't love so much:
What I Love:
Not specific to any one game in the series, "evolution" is something that permeates the series as a whole. It's easy to forget that the franchise began as a simple, top-down crime game with sprite-based graphics and the options of either "complete mission objectives" or "kill random pedestrians and gang members." It wasn't until GTA III that the series really leapt into the limelight and garnered the fervent following that has tailed it ever since. It was the first 3D game in the series, the first to offer players more to do in the world as a whole, and the first to truly immerse them. Vice City then gave its protagonist a voice and ramped up the plot, while San Andreas introduced RPG elements into the mix, proving that Rockstar isn't a company afraid of experimentation.
With Grand Theft Auto IV, though, the modern Rockstar approach to making games really came into its own. A complex and emotionally charged story, joined by two others in the title's subsequent expansion packs, coupled with excellent graphics and more satisfying combat mechanics set the stage for Red Dead Redemption and, we can only hope, for the upcoming Grand Theft Auto V. While IV did remove certain secondary and tertiary elements of San Andreas from the mix, it still stands as one of the most mature, complex stories told in gaming to date, which wouldn't have been possible without that constant experimentation that continually evolved the franchise.
This one is both a literal and a metaphorical boon. Grand Theft Auto games take place in huge open worlds, with tons of NPCs, many of whom one can interact with. The scale is incredible and, often, it feels as though one is traversing throughout a living, breathing city rather than a simulation thereof. It isn't just the size of the actual world or the care that goes into its construction that defines a GTA game, though. It's also the more notable characters who inhabit it: the protagonists, the antagonists, and everyone in-between. They flesh out their identities through interaction with one another, and through interaction with the player, whose character is also developed in this way.
Grand Theft Auto games also do a great job of dictating their rules. It's pretty clear what will and what won't get the cops on your tail, which means that rarely is there a frustrating moment in which the star meter arbitrarily rises and the blue and white cavalry descend upon you.
Freedom is important, because with a world this size, the player is going to want to mess around. Maybe you won't always feel like going to your next objective straight off (I know I often don't). Maybe you don't even want to do any of the structured activities strewn about the urban landscape. Instead, you just want to putz around and explore the limits of the system, explore the sort of anti-social behavior that is strongly discouraged in the real world by morality, ethics, and, y'know, our whole legal system.
Grand Theft Auto lets you do that. In fact, it encourages such behavior. You want the cops to go after you in a high-speed chase down a major thoroughfare. Want to hop onto the highway and launch yourself off the side into a fiery ball of destruction in the middle of downtown? Go for it. Also, as mentioned, there's a menagerie of more structured, constructive activities the game has for you to pursue.