It's entertaining as long as you don't take it seriously. If you do take it seriously it will frustrate the hell out of you.
In terms of violence; The manga has some, but the anime has very little.
Your biggest problem with Fairy Tail would be the asspull powerups Natsu gets, and all this "Friendship is power" bullcrap. In Fairy Tail your feelings is proportional to your strength, which is something a lot of people don't like.
But in my opinion the fights are great, it has a few memorable characters, the music is great, and it just has a good feeling to it. In fact if it were not for these things I wouldn't even watch it.
As for the plot; It seems to have started developing a plot slowly last arc, but there have been plenty of things that have happened in the past that have impacted on the story.
EDIT: Forgot to mention the fanservice, wayyyy to much fanservice.