While certainly lacking in the presentation department with it's very dated graphics, Dom4 more than makes up for it in it's charm. The game lets you take mythological lore from around the world and pit it in wars for ultimate domination. You will see Titans warring against undead legionares, yomi fighting against valkeries, and lich kings unleashing death on the men of Avalon.
To me, Dom4 feels like a Ck2/Total War-esque type of strategy game, where you fight to expand your territory, spread your dominion (religion), and develop your nation. Where it really shines is its deep magical paths and unit diversity. I play the game with my second monitor open to the Dom4 mod inspector (http://larzm42.github.io/dom4inspector/)
where I can compare and contrast every item, spell, unit, and magic site in the game. With 25 nations in each time period, combined with the numerous magic paths one can decide to branch into, their are many many combinations of strategies and development. In other words, no two players may play the same nation the same way, they may play off different strengths depending on how they designed their pretender (leading god of their nation).
This game to me is an easy to play, tough to master - which opens up for hours and hours of gameplay. You can play against the AI who offer a fair challenge (albeit becoming predicatble as you play more - such is expected with strategy AI), and when you seek a higher challenge it offers both real time and play by email multiplayer. I didn't think I would enjoy the play by email system but it's really relaxing to have a few games going at once and getting to do a turn or two per day before and after work/school. I always look forward to downloading my turns and seeing how my wars turned out, what kind of events popped out, and coming up with a plan for the next turn. All the while trying to formulate long term magic goals that will keep me relevant into the late game.
In short, if you enjoy strategy, fantasy, mythology, or games such as Total war, Paradox strategy titles, or even the Civ series, do yourself a favour and give Dominions 4 a try.