These are just some thoughts I had while playing. If they've been addressed before, my apologies for beating dead horses.
I like the Subway system. I think it's great for getting around quickly, and I don't think it reduces the size of the world too much since there are merits to walking to your destination rather than using the Subway.
I think the Better Learning line needs to be modified. Level 1 increases the max skills before slowdown from 20 to 21. So it only covers itself. Level 2 increases that number to 24, L3 to 28, L4 to 32, and L5 to 37. There are ~90 skills at the time of this post, so Better Learning will only allow for roughly one third of the skills to be learned before the research rate slows down. Granted, L5 Better Learning increases research rate by 20%. I don't know what the slowdown % is. If it's working as intended, lovely.
The ability to flip immediately to a missing ingredient in a recipe to craft it, then flip back to the original recipe once I've made it is extremely awesome and makes crafting more accessible. So well done there.
Finally, I especially enjoy that I can get achievements for doing an action a number of times that is not a multiple of 5. Getting an achievement for petting a tree 21 times is very lighthearted and makes me chuckle.
Thanks for making the game. It's very fun to play :)