I must warn you at this point: even if this is a children's anime, it is very gory, and has cruel themes going on (starvation, child slaughter, war...). But no sex nor rape, obviously. Many of the monster scenes would be considered way too scary for children today.
As of writing this, only half of the episodes have been subbed. I understand some japanese, so the lack of subtitles wasn't a problem, since the story is quite straightforward. Knowledge of old fashioned and slangy japanese is useful, if you wish to keep up with the characters' lines.
I haven't read the manga, so I didn't have any expectations when I started to watch this. The story took me by surprise! It was enjoyable and reminded me of some old japanese folk stories. I would compare the feeling to watching Mushishi, except that Dororo has lots of action going on and less monster lore thrown around.
The first half of the series has a gripping storyline, with a lot of character development. The episodes' storylines could span 2-3 episodes. After that the series gets a bit loose, and I can't help but feel the episodes have a filler feeling to them. They also change to the one-episode-per-storyline format, which didn't do good for the pacing.
The last episode ties things up hastily but is okay. The ending development could have started a bit sooner, so the pacing would've worked better.
I'm actually pleased that this anime stayed black and white. The colored pilot doesn't have the same eerie feeling. I also like it that they made Hyakkimaru look older than in the pilot. The animation is okay, though there are some wonky parts here and there. As an animator, I can forgive them.
I really liked the music in this series (though the opening theme is too catchy :D). If you like biwa, you'll like it too. The music reminded me of Ninja Scroll, which is my favorite. The sound design is old fashioned, and I recognized some nostalgic sound effects that were a norm even in the 80's.
Sometimes the growling sounds were more funny than threatening, and I would've liked more variety in female voices.
The first half of the show is a bit more focused on Hyakkimaru, and the last half on Dororo. It's not too black and white, but I would've liked the story to be more evenly divided between the two. I liked how Nota (the dog) also had important moments in the plot, and wasn't there only to look cute.
The series has a wide cast of secondary characters, of which some are more memorable than others. But I liked it how they were easily distinguishable from each other; a trait that isn't that well handled in more recent anime.
As mentioned before, the plot was great in the first half, but lost it grip in the second half. I did watch the whole series during a few days, so I guess it was gripping enough.
If you like wandering samurais, yokai and old school kids' anime, this is for you. This is like a children's version of Ninja Scroll and Mushishi put together. I'd say you could watch the first 13 episodes and skip the rest to the final one, without missing anything important in between.