The artwork and animation are perfect, in my opinion. It is great to be able to see where you can take actions given your cards, industries, resources, network and developments. The game has been very stable on both my iPad Air and my iPhone 4S (both iOS 9). As others have noted, a few improvements are needed:
The AIs do not offer "intermediate" level play. Although useful in gaining familiarity with the rules and mechanics of play, they do not pose any challenge. I never came close to losing to them, even though my only previous experience was a single game in cardboard with three other novice players, in which I was beaten handily.
UPDATE: You CAN view other players stacks to see their stage of development by clicking on their icon at the top of the summary chart pop-up. (I discovered this by accident.)
It is hard to see how industries develop. In particular, you cant see how many higher-level industry counters are available until you have reached that level.
The development action seems to require an inordinate number of clicks to complete.
The online play matching and interface could be improved. You cant invite others, there is no rating system and there is no kind of search or auto match feature. The ability to give a game you start a title is handy, though.