I don't mean to start a GTA fanboy flame war or anything, I was just curious. Thanks for the responses. I have a few disagreements though (a lot of the stuff you guys pointed out is strictly opinion-based):
huge distances to traverse through mostly empty areas; constant micromanaging of your character's health just to keep him the way you want him to be, as well as having to gain "experience" for ordinary game actions; the most difficult driving physics of the GTA3 trilogy, but neither realistic nor rewarding because of it...
I thought the countryside and desert were amazing, and a nice change to the series' constant cityscape. The open land created opportunity for a lot more activities. Being surrounded by buildings can feel very restrictive sometimes, and it gets boring. I thought Vice City's driving physics were the most frustrating, and thoroughly enjoy San Andreas' more realistic feel.
The fact that the story itself that drove the game was retarded in its presentation. I can relate to the main character's inner turmoil around being framed for the death of a police officer by a crooked cop who controls gang violence. Then I remember I'm playing a GTA game, which means in between cutscenes and missions I could very well spend my time killing dozens of very similar police officers for no apparent reason and with no consequence on the stories actions.
It's called a plot. It's supposed to make you want to continue with the story to see what happens.
Most of the side jobs in San Andreas, while adding variety, simply were not fun. The valet missions were outright boredom from start to finish, and the fact that you have to drive across town to get the valet uniform before you can perform them is like punishing you for being punished. The delivery missions were a large step back from the admittedly not-that-much-better Pizza Missions in Vice City, with the major difference being loss of atmosphere and retarded hit detection (slow down to a stop before you can drop off the item).
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The Ambulance missions are a degree in pure torture, about 20 times worse than they ever were in Vice City. The fact that all-of the non city areas you can do them in have confusing layouts is annoying, and the fact that you will most definitely begin being hungry when you try to do them all means you will most likely encounter the hilariously ironic "Can't Work Out Glitch." When added to the fact that towards the end of the game, your health is already maxed means that the ambulance missions don't even do anything but make your percentage go up. The multi-person drive-by similarly wrecks the vigilante missions.
They add replay value outside of the story (of which they're not required to advance, btw). A lot of the side jobs aren't too unrealistic, so I didn't feel they were a waste of time.
The graphics took a major step backwards texture wise. While I love how the cars/models are so much sharper and higher poly, every single environment and background in the game is specifically designed to prevent you from seeing anything. Put through a coffee filter is one way I've heard it described. When combined with the fact that no items are highlighted when you approach them anymore, it makes ability to remember weapons and item placement without some kind of map a journey of impossibility; especially when you can be standing right besides them in some areas and not see them at all.
I couldn't stand the cartoony colors of VC. I prefer the more realistic look of 3 and SA (and IV's even better in this respect).
The incredibly well laid out sections are either underutilized (San Fierro, Las Venturas) or ignored altogether (everything to the east of the Airplane Graveyard), making a good majority of the game take place around the terribly designed Los Santos and Back O' Beyond, where the poor layout makes it incredibly easy to travel for a good distance only to realize you are going the wrong way upon looking at the start menu map.
Like I said, I love the areas outside of the main cities, and I would have liked them to have been utilized more during the story.
As for the special outfits not having special abilities (cop uniform not giving you clearance anywhere), it didn't bother me. I only fly over Area 69 if I purposefully want to get into a dogfight, and I'll occasionally visit either base to grab a Patriot, but the stars are easy enough to lose in about a minute (safehouse trick) so I can continue on my way.
Otherwise, I agree with everything else (especially the traffic, the most annoying aspect of the game, imo).