I actually really liked GTA IV. And I thought the driving mechanics in it were great. It was by the far the most realistic/difficult to drive in, but felt so good when you got it right. I spent endless hours on the online races.
I agree that the tone was maybe more serious - but there was still plenty of funny moments, and as far as I remember GTA III was also pretty serious in tone (well from what I could gather from a protagonist who didn´t speak a word!). Certainly compared to Vice City and San Andreas. I actually liked Niko and the whole immigrant-in-America thing as a way to lead the story.
I remember when I was younger, I was always wanting them to make another GTA: London, as they did for the old top-down games. But in hindsight, despite being made a British company, GTA is a game that needs to be set in the States. Although the UK might be a mess as well with plenty to caricature, the USA is just so extreme and there is so much satire to be had, plus obviously pop culture references are always going to be more internationally understood. And a GTA set in a place without the USA´s gun culture just doesn´t make sense.
Another plus point with games set in the States, and certainly the San Andreas/California-based games, is there is a much bigger and more spectacular diversity of scenery for when the game ventures out of the city.
