Fairy Tail is a generic shounen manga about a guild full of 'mages', meaning, people who kick ass with things that cannot be explained with anything else but magic. I don't know about you, but when I think of magic, I think of Harry Potter, you know, people with wands, I don't think of people beating someone down with a fire punch. Anyways, these abilities are never explained in detail, nor are there any limitations on it, except of course, when the plot calls for it.
The main character is Natsu Dragneel, the pink haired boy who is just like any other loud-mouthed idiot from other shounen manga, who gets down to serious business when you hurt his friends. The second main character, who is just useless fanservice, is Lucy Heartfelia, who really only serves to get beaten up and have her clothes ripped up all the time (seriously, the amount of wardrobe changes she goes through only for it to be ruined the next chapter ...). There's not really a plot, other than 'awesome people do awesome stuff and get into awesome fights'. How awesome that is, is very much YMMV.
Right, did I mention Fairy Tail shoves the 'nakama' (for those less inclined with the cliche, it's all about the power of friendship) thing down your throat so much you want to throw up? This is the part where, if you think deeply about Fairy Tail, you'll hate it. If you treat it like the superficial entertainment it is, you'll fair a lot better.
The characters are nothing special, the plot is simply non existent, the fighting abilities are stupid and how powerful they are is based on how many friends they have backing them up, the fanservice (which he tries to hide ...) is stupid (no panty shots whatsoever, but he's okay with drawing every female with huge breast balloons and show them in suggestive poses and make them wear bunny suits, or have their clothes ripped off), and well ... the only thing Fairy Tail has got going is that the art evolved to be pretty damn good looking.