Well, it is.
In the run up to its release, the game was hyped as a landmark game for 2008, and was initially highly acclaimed by review sites. Having only played the game when it came out for the PC in 2009 (because I'm a lazy bastard who can't save money for a console), I began to realize that the game, while still good, is filled with problems that don't warrant the game being praised as it did.
Let's begin with the positives. The amount of the work put into designing Liberty City is nothing short of impressive, with more than enough believable landmarks, detailing, and hidden gems to outshine the likes of Stilwater, Steelport or even Panau. Vehicle design is also far more convincing than the some of the abominations seen in GTA San Andreas, Just Cause 2 or Saints Row 2; ditto with character and NPC animations. Soundtrack? Not bad.
That said, too much attention to detail as well as the shift towards realism may have been the reason less work was devoted to other elements of the game.
There's significantly less character customization and weapons to dabble with, plus planes (which is understandable) and tanks are absent. There is also a notable reduction of side-missions, with the remaining missions unreplayable once done.
Driving may be annoyingly tougher to certain players as more realistic driving mechanics mean inertia has to be taken into account when braking or cornering, and it's too easy to be dismounted from bikes. While the refined driveby mechanics and more complex hand-to-hand combat are fairly well executed, I couldn't help wondering if the cover system was a little unfinished, as it seemed like more could be done to improve mobility under cover (i.e. moving around corners or switching cover). Plus it's way too easy to die. I'm not even talking about getting shot; falling a mere five floors, getting rolled over by a car tire, getting thrown, or just standing on a moving train with full health may easily kill you; it doesn't happen in GTASA.
The biggest thorn is the friendship system. You just can't avoid friends calling asking to go out even if you set your phone not to take calls, which can become very annoying. The outings themselves can be pretty tedious, as you waste time taking them places.
It's good R* North acknowledges some of these problems with the DLC episodes.