I bought this game as a physical copy when it first came out in 2009 and later upgraded with the expansion. I don't think I've spent even remotely close to as much time in any other offline game as I have in this. I estimate it's gotten to be in the quadruple digits over the years. One thing I should note: I enjoy this game in two ways: building pretty and optimizing the economy - despite my many many hours of gameplay I've never used combat outside of the main scenarios. Not because the combat is bad but because it's just not an aspect of the game I'm looking to partake in, so keep that in mind:

Pros:
-very high replayability
-challenging scenarios and gameplay that constantly keeps you engaged
-extremely adaptable difficulty (you can adjust or toggle almost every aspect of the game to your liking)
-endless opportunities to fiddle with and optimize your trade routes and production chains
-tons of layout strategies to utilize as your cities grow and your empire expands
-beautiful graphics and atmosphere
-even after so many years there's a decent sized community around for multiplayer and third party tools like the production calculator and mods are still up and running

Cons:
-the game can get choppy in very lengthy endless games (we're talking huge populations and cities ~tens of hours into a single match - most people playing for casual fun probably won't get there)
-if you've never played this sort of game the quickly increasing, dynamic demands of your citizens can become a bit overwhelming, particularly with other things like trade and diplomacy happening simultaneously
-there are mini quests that grant very nice benefits that can be vital for optimizing later on. However, they can become a bit repetitive and tedious over long endless matches and unfortunately you cannot toggle them on or off once the match has started - you're stuck with whatever setting you picked prior to start