OK?
http://www.youtube.com/watch?v=9Gdz2rgs0zQ
In case people miss it, read the description of the video. The OP has a better system than the YT link.
EDIT: Here without any mods, on a i7 3770K non-OC'd:
http://www.youtube.com/watch?v=MtFwlsQZLPg
Looks perfectly playable and smooth to me.
I think you and I have different ideas of what "smooth" is. I watched your gameplay video without any mods, and your framerate dipped into the 30's.
I fired up the game just a moment ago to see how it runs maxed-out at 1080p on my 7870. I averaged around 30 frames per second (that's without recording). Is it playable? Sure. Is it perfectly smooth? Not at all. Subpar framerate combined with irregular dips and stutters doesn't make for smooth gameplay in my eyes.
Of course, both your CPU and GPU are better than mine, so I'm not surprised it runs better. However, saying that OP can "destroy the game" at max settings is a gross over-exaggeration.
That was an accurate description back in the day when a Core 2 Quad and GTX 280 were 'high end'. That time has passed however. Hell, my little brother's hand-me-down 4Ghz i5 760 and 69502GB run it like butter at 1080p with almost everything maxed. Maybe patches and drivers have really helped it over the years. It's been out for a really really long time now.
I pretty much have to agree with this, but wouldn't call the issues "crippling" for the most part. I've been playing it recently, i5-2500k / GTX660. Most of the game is smooth as silk, but then from time to time it will stutter and bog down. The problem usually resolves itself, but once or twice I have had to restart.
Sure. GTA4 is a relatively old game at this point, and hardware improvements come onto market quickly. But I don't know anyone who can argue against the fact that GTA4 is a technical disaster where optimization is concerned - regardless of when you play it, or how good your computer is.
When you take a 2008 video game, install it on a 2013 gaming computer, and the framerate still struggles to even meet the refresh rate of your cheap 60hz 1080p monitor, something seems wrong to me.