I have about 370 hours in the game. Compared to SimCity 4, it's not quite as challenging and perhaps less complex. It's hard to "fail" in this game, traffic is pretty much the only thing you have to worry about (it can get really bad). But it's a great game if you like just creating and designing cities. There's an absolute ton of mods for it in the workshop.
The AD DLC is worth it for the the tourism zones.
The Snowfall DLC would be much better if it added actual seasons, rather than special "winter maps" completely separate from the regular maps. There's a mod that lets you convert existing cities to/from winter, but meh. Building in the winter is annoying, everything looks the same because of the snow cover. The DLC also adds trams however, which are really cool if you like to build out the public transport.