At a glance, it might be easy to confuse "Fairy Tail" with one of any number of fantasy role-playing games, especially those on a computer. Natsu, Lucy, Gray, and Happy the cat are members of Fairy Tail, the largest magician's guild in the world. Through Fairy Tail, they can pick up quests and try to solve them for large rewards. Sound familiar? It should. It's the mechanic for a lot of programmed adventures, an easy way to serve up a mission for players to attempt.
What makes "Fairy Tail" succeed, though, isn't so much how the characters get started, but what they do next. Because trust me, these characters are nothing but fun. They aren't always all gung-ho (I love that Lucy has no desire to head out on the latest quest until she finds out that a Golden Key is part of the reward), and they've all got their own motivations and desires. The fact that Mashima's able to keep finding a way for Natsu and Gray to work together despite their mutual dislike is impressive; it's yet to feel forced, and the book is that much stronger because of their continual clashing even as they push forward.
I also really like the "Fairy Tail" magic system, and how no one's abilities are quite the same. Gray's control over ice reminds me a bit of martial arts in books like "Naruto," where people train over time to gain new abilities, but there are still skills within abilities. The fact that Gray's latest opponent (also an ice wizard) scoffs at Gray for not being able to perform one-handed really brought that comparison home to me, but it also makes everyone's attacks slightly more up in the air and questionable than, "If you say the words it will automatically work." On the other hand, Natsu's fire powers having to do with his emotional state brings to mind the Incredible Hulk, and I also love that Natsu and Gray are predisposed to dislike each other because of the powers (ice and fire) that they wield. Best of all, though, is Lucy and her channeling powers that are connected to Celestial Keys, able to summon different astrological-themed beings to help her out. It's a nice twist on the normal wizard abilities, and Mashima plays this structure with great effect.
Add in crisp, clean, fast-moving art and it's easy to see why "Fairy Tail" is such a great book. His character designs are great and at times more than a little unusual; it's not at all uncommon to turn the page and suddenly mutter to yourself, "Did they just get attacked by a 50-foot rat wearing lingerie?" A lot of the humor of the book is courtesy the art, and Mashima works it quite well.
"Fairy Tail" is easily one of my favorite new series of the year; it's hysterically funny but at the same time can bring out a serious side when it needs to. I've yet to introduce this manga series to a friend who hasn't liked it, and I bet you will too.