Fairies are cool.

As an Offensive type, they're rubbish, unless they have some coverage move to kill the endless defensive steel-types in the game, or they have a decent secondary STAB. Those that do, generally lack in either speed or offense, and end up using bulk, set-up moves, or priority to get past those limitations. So, in general, they're mostly walls, support, or bulky sweepers. 

Defensively however, they are absolutely fantastic. Between the Fighting and Dark resists, there is very little the once nigh-OP Machamp can do against them. Conkeldurr is now less of a problem. Lesser fighting-types are even less of a threat. The Dragon immunity even means that beasts that once ran rampant across the metagame, now have actual counters. Togekiss, for one, is immune to both of Garchomps STABs, has enough bulk to eat the occasional fire fang, and can force it out with STAB moonblast. This is the first time anyones ever been able to say "Garchomp has a true counter".

So yeah, they're pretty alright.