If you want things to go wrong, I just hope your expectations for 'things going wrong' are very high, because while the first hour or two are likely to be idyllic and lull you into a sense of 'jeez, this game got so simple and casual', your design decisions from the first few minutes are likely to come back and spiral you into armaggeddon with a plethora of issues. I don't want to make too many broad statements about this particular version of sim city because of the high tensions floating around about it, but I will say that it isn't as easy as it seems. You'll notice that around the time you have your first city hit 120k citizens without any initial urban planning.
Edit -- if you really want an example: mass transit. Because traffic is handled in real time, you can't simply go 'well, my city is utterly gridlocked, guess I'll plop down some busses.' You need to get the mass transit system in place reasonably early, because it adheres to the same traffic issues as everything else. If everything is gridlocked already, your busses will be stuck in traffic for so long each day that commuters will simply get fed up with waiting for the bus (~70-80 minute wait times seem to be about the most they'll put up with, with 60 minutes being the norm for heavily taxed bus systems and 30 minutes being the optimal wait time vs bus upkeep) and hop into their cars, thus adding back into the traffic problems that prevent your busses from getting where they need to go swiftly. Planning ahead is the name of the game, not reacting to issues as they come.