Evil Genius is a brilliant and hilarious portrayal of the James Bond-style supervillain. Everything about the game, from the military-like corridors to the 60s-esque computers, works visually with the theme. Watching your minions train and do other things around the base is amusing, and while your world missions just involve sending minions to points on a map, it's still satisfying to watch your money grow.
The gameplay is good - better, I think, than some of the reviews were saying back when this game came out. It takes some getting used to - you can't directly control your minions movements (you can with your henchmen, but without some minion support, they won't survive a team of enemy agents). But once you get the hang of using base alarms and enemy tags, it's not hard to get your minions to do what you want them to do.
Fun game all around, and the slight control and gameplay issues are easily overridden by the style and sheer fun of being a 60s supervillain.