It's not just about the map size. The traffic algorithm is much better and each citizen is simulated realistically (they have permanent jobs, get married, die, etc). You have way more public transit options than what was available in Simcity 2013. The district system is brilliant and you can name and follow almost any object in the game. You also get to create your own maps and the water simulation is truly cutting edge. 

Of course the game isn't perfect. It doesn't have the day and night cycle so you don't get to see your city lighting up. The gameplay becomes a bit monotonous after a while especially given the fact that there are no disasters. Its industry specialization definitely lacks depth; the graphics department and its cartoonish color palettes have some room for improvement. There are some arbitrary limits to the number of objects that can be displayed (road limit, pop limit, tree limit, etc) because the game was written using Unity. 

It's important to note, however, that the devs have already acknowledged some of the criticisms and are interested in future DLCs for some of the highly sought after features. Just last month they patched up some major bugs and added the European theme and tunnels for free. Plus, the modding community for C-S has been much more active than Simcity's counterpart as modding was encouraged even before the release. My point is: this game has much more potential than some of you may think. i.e. the bubble, if there was any to begin with, is not about to burst any time soon.