Cities in Motion 2 is a fantastic game. It is an insane amount of fun to build these lines, expand the city, tune every little detail about your routes and just keep on expanding. Yesterday, my wife and I played a co-op multiplayer game for the better part of the day without even realising how the time went by, Civilization-style. I bought the game on Friday evening and by now (Monday morning), I've clocked 19+ hours in Steam. If you're like me, you'll definitely get your money's worth from this game.
However, there are some minor flaws in this game, too. It's nothing too major and won't keep you from enjoying the game, more like little annoyances. For example, streets can't be upgraded, so in order to add bus lanes to a street, you have to demolish it first and rebuild it after. If none of your routes go through that street, it's just time-consuming and a bit of a pain, but if you have bus stops in that street, those will be deleted and you will have to place new ones and make sure to adjust all relevant routes to use the new stops.
There are some more minor issues, but developer Paradox Interactive actively solicits user feedback, so I hope these issues will be fixed in a patch rather soon.
All in all, I can whole-heartidly recommend this game to anyone who likes building things.