I'll be honest right from the start, I enjoyed Monster a lot but I can't help but feel it could have been slightly better. I'll explain why in each paragraph for the story, art and so on, but I will say it's well worth your time if you have patience. It is 74 episodes long, adding up to more than 30 hours of solid viewing time.
Story - 8/10
As mentioned at 74 episodes Monster is very long, but the story is captivating and often enthralling. I do feel the entire series probably could have cut out a fair bit of the more pointless scenes (and even perhaps the occasional episode), in my opinion I would have probably given the story aspect of Monster a higher score if there wasn't so much filler in between the more interesting moments as it all builds towards a thrilling final ten episodes or so. However the longevity of the series has its advantages, primarily with character development and attention to detail. For example there are several themes of historical significance from the Berlin Wall coming down to Neo-Nazis making a nuisance of themselves, and the various cultural quirks from the different countries in Western Europe primary protagonist Doctor Tenma visits are captured flawlessly.
Art - 8/10
While there is little I can think of that particularly stands out regarding the art and animation found in Monster it's all put together in a very realistic manner. The scenery looks excellent without being too elaborate and the attention to detail when it comes to trees or hair blowing in the wind is excellent. What impressed me most was the consistency of the character animation, the quality never dropped or changed significantly at any time and the transition in age between the characters at the beginning and end of the anime was a particular highlight of mine. Much like in real life it was hard to spot any major gradual changes in age until seeing a photograph of someone ten years previously, I thought that was very well done.
Sound - 6/10
Probably the weakest aspect of Monster was the sound and music. The voice acting was easily the best part, with character like Lunge/Runge and Doctor Tenma himself being voiced to perfection. The general background sounds such as traffic, gunshots, rain and so on were also adequate, but Monster had a less than interesting soundtrack to accompany that. The ending theme used up to around episode 32 I thought was an exceptional piece of music that really fitted in well with the overall feeling of the anime, but once they changed it to the frankly stranger second piece used until the very end of the series I was less than impressed.
Character - 10/10
One of the advantages of watching an anime as long as Monster is that there is plenty of time for individual character development. There is a very large cast, but the writers do an exceptional job of allowing a lot of time for the viewer to become emotionally attached to a lot of the more major characters. There's a fairly standard divide of good guys vs bad guys, either aligned with protagonist Tenma or antagonist Johan one way or another. Without spoiling too much there are a substantial amount of deaths throughout the series, tugging at your emotions as either a character you've come to love or one you've come to despise finally meets his or her end. It's all done to perfection.
Enjoyment - 9/10
Despite various flaws I enjoyed Monster very much. It's by no means the best anime I've watched but it's definitely the most unique, thought-provoking and one where at times I couldn't wait to find out what happened next; I often watched half a dozen episodes in one sitting which is rare for me to do. The only negative point I want to make is with the slow pace of the series, particularly towards the beginning, at it was at times a slight struggle to get through but once I did I never regretted it.
Overall - 8.2/10
