the only thing i dont like about them is they dont last long for the price of a marker. Other then that i love them and they are a breeze to work with. They are pricey, so look around for deals. I just use the brush mostly, blends out easier then the wedge.
I've had issues with their fineliners. The markers themselves are fine, I find them no different than any other artist's marker. Personally, I prefer to buy Letraset promarkers which are less expensive and IMO the same quality. The one advantage Copic does have is that I believe they are refillable, but between replacing nibs, ink and the fact that they're not sold locally here it's just not a logical investment for me.
Overall, yes I am pleased with the results that Copic gives, but they won't make you a better artist. Like any medium it takes time and practice to manipulate the medium to your liking. Even I'm still improving with the way I use Copics. Personality I found them relatively easy to get use to though I'm still trying to find a way to use them to their (and my) fullest potential.
Like Parabuteo said check out the tutorials and youtube videos. There are some really nice ones out there.