I really don't remember San Andreas ever looking that bad. To me, it looks like Gamespot took the PC version and scaled the graphics options back some in order to make the IV/San Andreas differences more dramatic. Generally, the texturing looked better (on the PS2 version, at least) than these screenshots seem to show. Also, I don't feel the cars in San Andreas were "boxy" either. Compared to 3 and Vice City, the cars, particularly the police cruisers, looked actually pretty good.
bwing55543's comments