Right off the bat I have to disagree with his comparison to Bioshock. Albeit it was simply about plot development, but I don't think he 'gets it' when we're talking sandbox vs. linear FPS.
Bioshock created a story, and then the environment in which to weave it. Far easier, IMO, than knowing you have this incredibly open world, where you are some ant in a sandbox, and then trying to weave a story into it. Especially a story grounded in some sort of reality.
You could come up with a linear FPS just by writing words on a dart board and throwing three darts: 'Underwater', 'Plot Twists', 'Special Powers'. Wow, that sounds sweet! Of course, substitute 'Underwater' for 'Outerspace' and you have System Shock...
I think it's far harder to take a world and weave a character and story into it. GTA had roots, it had expectations, and it was expected to follow those, and make them better. IMO, that deserves a lot more focus and credit then simply saying 'the story is great, just like Bioshock!'
Otherwise, I wholeheartedly agree with the article. I've played for about a dozen hours or so because of the W.C.J. (wife, child, job), and I'm like 6% through. I like to take my time, and will probably play this game solely for the next 3 or 4 months (sorry MGS).
It's not without it's flaws. It certainly doesn't look as nice on a big screen HD as it does in the previews. The driving camera is a bit awkward at time (though, you can adjust it nicely), the cover mechanic is like Gears of War version 0.3b, sometimes juggling peoples attitudes for you gets overwhelming, some missions are built to fail on the first run, and probably a few other things as well.
That being said, all the minor flaws are completely overshadowed by the people (you care about them), the plot (so far it's a really great and believable story), and just the 'vast while not being too vast' of it all. It really is a next gen GTA3 2, whereas VC and SA were like GTA3 expansions.