Done with the single player main storyline last night (70% completion rate). Took me around 35 hours, give or take, to complete the main storyline plus a whole bunch of other stuff. Just have a few more Strangers & Freaks missions to complete. I loved the game, BUT this is not to say that it didn't have any faults.
On the positive side, I feel Rockstar really did a fantastic job of creating Los Santos and Blaine County in a vastly detailed and vivid manner. It's hard to believe they pulled off this level of detail from 8 year old console hardware. They also managed to implement a good amount of gameplay changes like the weapon selection wheel, characters switching, quick-save, special ability, new means of exploration etc. I liked playing as Michael and Trevor, but hated Franklin's character. The side activities were quite fun and even after the main game ended, there was a lots more to do. The entire look and feel of Los Santos in HD was a treat to watch, especially the night time environment.
On the downside, I feel Rockstar could have really made better side characters. I remember GTA IV had so many memorable bunch of side characters and their missions were so much fun, but this game had some really dull NPCs. Some heists could have been designed differently and could have been better. The chopper controls and tank movements with the characters still seem to be an inherent problem, this seriously needs to be addressed. The radio stations and soundtracks were completely boring, except for a few tracks. The writing is certain aspects was really annoying, especially with Lamar's character. It was so annoying to hear "nigga" being spilled out in almost every sentence. The "hang-out" sessions in GTA IV was something which I really enjoyed. I could call almost any of my contacts and they would come right over. In this game, I managed to go out with Amanda only, the rest would either be busy and wouldn't have the option to "hang-out". The options were really limited.
That being said, like most, I chose the 'C' option in the end. That was again not up to the mark. In GTA IV, the ending was fueled with a great deal of rage on Niko's part, which made it that much more interesting. This, however, was more predictable. Come to think of it, I can't really understand why they would even provide option 'A' and 'B' in the first place. Nevertheless, I guess they had to provide some sort of choice in the end.
So to sum it up, it delivered on the hype, with a few hic-ups, but still managed to be highly entertaining and fun. Good work as always Rockstar!