In a nutshell? Your favorite mutants revamped for our times. I was skeptical about picking this up since I am a huge purist, and I didn't like the idea of people messing up things I think aren't broken, but it turns out, change can be good.
X-men Season One casts the original Five: Cyclops, Beast, Marvel Girl, Iceman, and Angel and follows them as they try to understand and control their powers. The story is told through Jean Grey, the newest member of the team. And though she has never been a favorite character of mine (ever), I thought that she was written as an extremely likable, accessible, and grounded character-- exactly how I imagine new-to-comics readers approach the daunting, continuity-filled world of comic books. The X-men romp around doing their Danger Room exercises, getting trapped in the Savage Land, meeting the members of the Brotherhood of Evil Mutants, and realizing that not everything is as black and white as they thought things would be.
Dennis Hopeless (who also penned the amazing Legion of Monsters) , I think, captured exactly how contemporary teens would react if they one day awoke with powers they had inexplicably contracted (read: extremely annoying and hopelessly naive). Jamie McKelvie's bright and clean art (as in Phonogram and The Defenders) works amazingly with storyline, so I forgive him for portraying Iceman as Justin Beiber (or is is the other way around?)
A great read for newbies who wanna get into reading comics but are unsure where to start. But it's an entertaining read for long-time fans as well.