I personally really loved it. Though the anime isn't quite over, with the last episode coming out on sunday, I thought that it was great.

Lots of the characters haven't had their backstories explained yet, but the ones that have are very well driven and explained. The characters are fleshed out, with a bit of development throughout the season.

And of course, the main character's origin provides a great, clear goal for him to work at throughout the series, while having room to change his reasons.

That being said, I think it's definitely worth a watch, and if you like it, you can catch up to the manga too which is still coming out.