Between a lot of work and some more work, I've managed to finish Diablo III on a wizard. It was a good choice for a game, given it is easy to just log off and finish later, with the itemization and stats much more simplified when compared to the earlier versions of the game. I'll be quick to list the points of the game that impressed me the most:
The fashion designer of this team is better than WoW's: the gear looks pretty and makes you want to progress. No, really, I enjoyed getting new gear to look pretty in flowing robes as opposed to kill monsters quickly. Believe me, monsters die quick enough with the wizard.
It is not difficult to pick gear: aside from the brainless calculator, stats are easy to figure out and there is no more point distribution drama, to ponder about different builds and not being able to reset.
Runes are more flexible than talent trees: you can change at any point the spells you use. No more buying and regretting latter, no more build a spell just because it is required for the next level like it happened on Diablo 1. Same thing for the companions, you can change their skills at any point.
Gems are not set in stone: believe it or not, the jeweler in this game is so GOOD that he mastered the ability to remove a gem from a setting! So no more drama over socketing gems that are still not fully upgraded.
Everybody's got a journal: there are a lot of pieces of lore throughout the game, like bestiaries and journals that help you catch up with the story or find out what happened between Diablo 1, 2 and finally 3. Some have nice touches of humor, which is always helpful. Dialogues are also nice and to the point, with some humor here and there.
Online gameplay: I haven't tried to join public games, and I don't see myself doing it at any point soon, simply because I have a limited time to play, and would rather just be either by myself or in the company of people who already know my style of playing. With that said, I could have had the game as offline only, but the few times I played with friends, it was fun.
"Replayability": I intend to finish the game again with a different class, just not sure which yet. I'll also play it again on my wizard to reach the spells on the higher levels, and also to play with my friends in the more difficult levels.
Tristram Cathedral still exists: so unexplained. I personally would have imploded the place after the events of the first game, used some good concrete at the entrance and built a shopping mall on top. But these folks just like Tristram I suppose.
Overall, I think the game is too expensive. I finished it way too fast given I don't have much free time right now, and that I am the "explorer" kind of player who'll open all the maps and clear everything before moving on. The story is nice, but some of the plots I was able to guess, while others seemed too familiar with something I had already seen. It is a great game though, I had a lot of fun and know what I'll be able to play it again a couple more times and still be entertained. I suppose the "replayability" is the selling point when looking at the price tag.