Episodes 1-10 were amazing. I noticed decline in quality following them but it held itself together just enough until the final episodes. The anime ends on a cliffhanger, which sets up a second season that never came to be.
With that, the manga bares mentioning because the story doesn't end there. I recommend reading the manga from start to finish because while being a continuation, it also adds further context to scenes in the anime.
I'm also a big fan of the character design. The character's attire isn't big and bulky, instead it's slick and minimal. The minimalism also trickles down to the color pallet used on the characters. Shades of grey, yellow and white are all present. They aren't as expressive as colors like red or blue but they blend well and aren't too bright. The combination of both attire and color pallet results in something very striking and iconic. In other words it's something that's very stylish while also not surrendering itself to fan service. In fact, the character design is the biggest thing that drew me into Claymore, outside the setting.
I also thought the music and voice acting, English dub to be more precise, despite a certain character or two, were solid. I wasn't a big fan of the intro and outro at first but it did grow on me some 13 episodes in.
In closing, I don't see a second season possible. It's been what 14 years since the series debut? If you watch and like what you see, the manga is the way to go. Most volumes are readily available in physical format. I would love to see a second season but I'm content with the manga.
If you're a fan of Berserk or games like Devil May Cry, I recommend giving it a watch.