This is a light shounen (no blood & gore) and a good iteration of the Demons vs Humans theme, in this case in the form of exorcists. Perhaps, one of the best parts of the story is the implied premise that ponders: Are we born good or evil, or is this the result of the environment and how we are raised? Can tolerance and kindness transform someone who should be the embodiment of evil into an asset for society?

"Blue Exorcist is a great anime for any shounen fan out there, or anyone that just wants a taste of anime for the first time.

Published by A-1 Pictures (Black Butler, Sword Art Online, and various other titles), Blue Exorcist provides enjoyment with its variety of characters and nice animation. It focuses on the ironic idea of a demon killing demons; and, not just any demon, but Satan. The first episode goes directly into the story, and, at least for me, hooked my attention. The introduction to this series was well-thought out, even if it was in a few episodes. The thrilling soundtrack produced by Hiroyuki Sawano (Attack on Titan, Kill la Kill) keeps one on their feet through all the battle scenes. 

Blue Exorcist has left an impact on me through its beautiful way of conveying the thoughts and feelings of all the characters. It teaches one about sacrifice for those close to them, and the challenges one must overcome to achieve their dream." -ToastersOverdose

I recommend you watch without fillers:

• Watch S1 Episodes 1-5
• Skip S1 Filler Episode 6 - It's just comic relief.
• Watch S1 Episodes 7-10
• Optional S1 Filler Episode 11 
  • This filler is ok, but it goes nowhere within the main story, it ends up being mostly comic relief and average.
• Watch S1 Episodes 12-16
• Watch S1 Episodes 17 up to 19 minutes, before the fillers start.
  • At this point, the ending of S1 starts diverging significantly from the manga. And this filler ending of the first season is ignored in the second season anyway, with the anime story timeline once again following the narrative of the manga, so it's best to skip for best continuity of the story.
• Skip S1 Filler Episodes 18-25 
  • I don't recommend you watch this yet in order to avoid spoiling parts of the better story from the Kyoto Saga.

The dub is great.

• Watch S2 Kyoto Saga in full, Episodes 1-12 (26-37)
• Optional S1 Filler Episodes 18-25
  • The story actually starts in S1 Episodes 17 at 19 minutes.
  • The filler story of season 1 is not terrible (although it contradicts itself at some points) but is perhaps best left to the end, as an alternative ending. Just remember that is filler, not canon.

The dub is great.

Watch.

The movie is a side story, an extra mission to exorcise demons on a train, but not related to the main story. It expects you to know the characters, so you can't watch it before watching the series. The graphics are amazing, it may be worth watching just for the 'eye candy', but it has a good story too. If you enjoy the series, then you'll probably like it.

'To start off this movie is probably one of the bests I have seen even though it is only a side story, this movie is detailed and intriguing as you watch each scene. The animation is just about perfect, I didn't see many problems, and the designs and scenery are spot-on if you are looking for a movie with amazing animation...here you go ^_^' -AngelBeatsYui

The dub is great!

Optional.

This is a cute story that focuses on Kuro, but very predictable and average at best. You may like it better if you enjoy slice-of-life, not as much if you expect some action.

'Don't watch unless you've seen the rest of the series! May contain slight spoilers if you're not far enough along.  I liked how there were many different character cameos in this special.  And the ending got me, way too cute and sweet.  Nothing mind-blowing but fit with the series and was adorable.' -SirenInu

Optional.

These are short comedy sketches and as such, they vary in quality per each episode. Comedy is hard to rate as it's very subjective and largely depends on how much they make you laugh, so I recommend you try a few episodes and decide for yourself. Personally, I found it average.

'Each is only a minute and a half long, but it was fun seeing the characters out of the normal story setting. You get to learn some new things about some of your favorite characters and they're really cute and funny. ^_^' -chickenparade

Skip.

This is just a comedy sketch, but it's not very good at all.

Optional.

These are unaired episodes bundled with the 19th and 20th limited edition volumes of the Blue Exorcist manga.

They are mostly slice-of-life and comedy, so only people that enjoy those genres may find them good. Don't expect much action.

• OVA 1: The story centers around Mamushi Hojo and Juzo Shima when they were students studying at the True Cross Academy, and acted as a prelude to the events that would transpire in the Kyoto Saga Arc. But it's better to watch after Season 2 in order to avoid spoilers, you'll enjoy it better this way because you'll know who the characters are.
• OVA 2: The story centers around Renzo Shima's perspective during his early days at True Cross Academy.

Skip.

This was a terrible season, below average in my opinion. The change of studio and director probably affected the season. I think the story had potential, but it was handled in a lackluster way, just trying to get from point A to point B without proper buildup and conveying meaningful feelings. There are no convincing explanations for the events and character changes and the ending is quite stupid. It's a failure of direction in my opinion.

So unless the upcoming S4 Beyond the Snow Saga picks up the quality, I recommend skipping this season and saving your time with better anime. It may be necessary to watch this season to understand S4, but only if S4 proves successful, as it stands right now, S2 is the highlight, and is not worth spending 4 hours of your life on S3.

(Currently in Development)