That's what I'm saying. It's like if some one made a painting and says "I used all the colors and have all kinds of shapes, now what do I do?" Personally, the cool challenge in a city builder comes from what you want to build, not just solving what the game throws at you.
15 hours in and I'm kind of getting the same feeling. There is no real difficulty besides traffic and keeping your cash in the green, if the game stays this way alot of people will buy the game, love it ( like I did ) but get bored after a couple of weeks and go play something else.
Games like civ4, hearts of iron and the old famous city building games all have one special thing. You need to be able to do new things, build new things, plan new things, all the time during the game. For instance take Zeus, one of my old favourite city games. You had missions with seperate challenges, get x population, produce x amount of goods, but also things like get x amount of wine, those buildings, those amount of rich people, etc. etc. to finally call in Hercules to put the smack down on that Hydra monster that's been killing your farms constantly

Civ4 always has new tech, new buildings to build, new units to attack/defend with, new resources to find/trade for, etc.
New things, new buildings, new challenges, new 'tech' is what the game needs in the future.
What I love so far:
*very easy to use intuitive UI and road building system
*hasn't crashed on me once so far, very smooth fps without hiccups
*steam workshop ( thank you for the parking lots guys! )
*looks and feels realistic
*great price for such a good game
*great community and developer comments/feedback
What needs improving:
*challenge curve or the lack there of, adding a minimod that makes everything more expensive isn't gonna cut it guys I'm sorry..
*lack of disasters, no bad weather, traffic accidents, riots, bad economy, etc. Everything is happy as long as they got a park in the area

*there's a bug or weird feature where there is no commercial demand what so ever, alot of people have it and it needs a priority fix imo

*slightly more control over lanes in highway merges would be great, we all know the 'cars insisting on driving in the same lane because they think 2 turns in advance ' by now..
*bus tweaking, I redid my bus routes now and it's good again but apparently the AI sends 50 busses on a single track if the route is too long clogging up my entire highway

Perhaps add an express bus for long way routes?
*more information on public transport, how many passengers on each line for instance? With alot of routes the transport overview with all the coloured lines gets a bit messy to look at..
Great game though so far, still enjoying it but after a couple of days I'm starting to get a little bored already

There is only so much road-making-OCD can do for a man

o