Since me having several dozend hours of playtime experience, It would like to mention some more improvements not listed so far:
Gameplay / Bugs / Balancing:
* Pedestrians as well as waiting passengers disappear when building tram tracks or upgrading a street. Even if they’re waiting in a rail station grouped with a proximate bus stop. This can create a massive income drop if it concerns a rail station with several lines – in difficult it can be a neckbraker
* same counts for adding or extending streets
* difference between levels of difficulty normal and difficult is way too high. In normal after a few decades I have to expand excessively in order to get rid of my millions. In difficult my balance doesn’t allow even a single train line. An alternative way would be to have five instead of three levels.
* add an option fill to 1/4, half, 3/4 additionally to filling one cargo type completely
* add an option for a maximum waiting time in combination with filling to a certain amount
* trains should automatically change the track when the normal path is blocked. I had the situation several times that two tracks where available for two lines but both trains chose the same platform to arrive and didn’t want to chance it even though I rotated the waiting one back and forth
* bus lines should spread over available platforms. Why do three tram lines choose the same platform in a bus station when there are four available?
GUI:
* Windows should be closable by right click (could be optional) instead of having to aim on the small x.
* Vehicle windows should optionally open without tracking camera. On my rather old machine (Core 2 Q6600) it really slows down the performance when buying several (e. g. ten) vehicles at once, cause then also ten registers with a small camera following the carriage/truck/whatever open. The curser also judders which can be really annoying concidering the point previously mentioned.
* Windows should not open behind fixed GUI elements. When coosing a vehicle or depot outside the screen, the corresponding register is placed at the very edge of the screen – even if it’s behind the building menu, the main menu or the money/XP display
Features:
* rail and big bus stations with two street connections. In 1850 it might be appropriate to have a rail stations oriented to only the front side but in 1970 most stations have a connection to both sides of the track. This would also support growing of the city around the station. Big bus stations also could have two entrances (even to one side) in order to prevent traffic jams in front of the one small entry.
* rail stations with the entrance at one end of the platform. This way you wouldn’t have to block a factory for cars or create detours in order to place the cargo station near to it.