A bunch of answers, sorry for the delay, had to sleep a bit
So the game has a stats page to check your former scores.
It does not have a cooperative AI because it doesnt need any. It's a coop game, you either play solo with one god, or with many (six). It can be played as a solitaire, or you pass and play with your friends. You'll fight against the game rules (the baddies' cards) either way. There is a steep learning curve I presume, and it definitely helps if you play some games solo before you explain it to others. (GS took me a day to grasp everything, of course I wasnt familiar with the concept). The board -- as beautiful as it is -- can be intimidating, but after some plays it just clicks. The in-game tutorial wont help you a lot, you have to read the rulebook and check some youtube videos from the original game. There are some informative ones out there. About retina I dont know, you may be right; the game looks stunning as it is. Lets hope the graphical overhaul won't screw the nice 80MB size of the app, and wont cause any slowdowns on older devices ;