Civilization V is one of the most accessible games in the series. The in-game Civopedia, advisors, and tutorials offer plenty of learning opportunities making it easier to learn to play Civ than ever before. Apart from that the revamped combat and hexagonal grid opens up a much greater variety of tactical play during combat. If you've never played Civ now would be a great time to try it out. If you loved the previous games in the series you'll find that Civ V removes many of the tedious elements from previous games (ie, religion from Civ IV) and improves upon the combat mechanics in general. I highly recommend it!