Yeah I agree with some of this, the game simply wasnt big/long enough for me. It took me a while to complete it (not 100% yet), but others had it done in a day or 2.
When you boast about having THE biggest open world map EVER, you need to cover more areas, and make use of some more iconic places. I mean, there were NO interactions with the prison (other than a random escapee who'll try to jack your car and/or shoot you), the NOOSE HQ, all the industrial factories (other than one late in the game) and definitely could have touched more on the underwater areas. Yes, you can go underwater twice in a sub (depending on your choices in one of the "Heist" Missions, and also once with scuba gear, but the size of the map, should have saw more missions underwater. - note, you can purchase a dock which will give you access to a sub, for a 2hr mission which will net you around $600k, but only if you WANT to, not HAVE to.
So many buildings, but so few entry points, simply no where NEAR enough interaction with the buildings, and shops, etc. Yes, we can rob shops, but NONE of the restaurants! Should have had a lot more property to buy. I'm right on the $500m mark with each character, with 2 more Assassination Missions (Lester's missions for Franklin), which should see me tip the $1.5b-$2b mark, and with the Golf Club the most expensive at $150m, what do I do after that!?! Should have been more places to spend your coin. - and with the current car/garage glitches which will sometimes lose your cars, you don't wanna be spending millions on the exotic cars if they're going to disappear.
I was shattered to see no car export side missions at the docks, like previous GTAs. Could have been a real money maker for the none-investors on the Stock Markets! And how crap was it for Franklin to be able to buy a Los Customs Shop, all the way in hicksville (Trevor Country) when he's a city/hood boy, only to not have access to free shit in other LC shops. ie, you have to drive all the way out to pimp your ride, only to smash it up on your trip back to the City! IMO, anyone of these 3 characters should have had access to buy any property!
That's my little rant done, on to the plus-sides! I really liked the characters, thought they were well designed, and unveiled. Don't forget that we're dealing with 3 dudes all at once, not just dealing with a single "Niko Belic" or "Claude", so their story/history can't be fully told entirely through the main story, only in short glimpses, since we're always switching characters. It would have been nice to be able to impulsively interact with each character, rather than during missions, or by phoning them to hangout. ie, Franklin to rock up at Michael's house, and have a beer or something random as opposed to something scripted.
Other than what I consider a short game (given the map size), there's a stack of side missions, the Freaks and Strangers missions were cool, but again, not enough on such a massive map. The always-expected "collect this" and "jump that" bonuses will have us playing a little longer, but only because there's a lot of them, and without the guides, they're very had to find.
Massive, massive game, but could have been bigger! The hints of upcoming DLCs might make things more interesting, but we don't yet know if they'll be single player, or Online Mode....
Speaking of, Online Mode IS something special. Same size open-world map, with a lot to do, but if you're the lone wolf gamer, you'll find yourself short on entertainment after not too long. The emphasis on "Crews" is huge, and most definitely a necessity if you want to get anywhere playing Online. Too many missions require at least 2 people, and running with randoms with no communications, simply won't do.
Making money Online is really tough early on. I play a lot on my own, and am currently residing to robbing convenient stores for $1500 a pop (and 2-3 stars depending on who I shoot), and with not enough cash to buy an apartment, it's sometimes tough making my way to an ATM to deposit the money safely.
Still a top game, and plenty left for me to do and see, and if anyone can ever crack the code about the Mt Chiliad and the UFO mysteries, we'll have more to see and do no doubt!!