I have read the WN, so my review may not too objective. Overall, there's not too many differences between Anime and WN from those episodes I have watched.
Mushoku Tensei is an unique isekai because the MC's life starting from baby while carrying previous life memory, Trauma. MC also have to learning different culture, language and common sense.
Mushoku Tensei is all about Rudeus Greyrat's Life in this new world. So don't expect Rudeus Greyrat fighting to save the world.
Character 10/10:
Rudeus Greyrat ( Rudy ): A Perverted NEET that reincarnated and try to live seriously in this new life. However, his perverted action won't change through the story. So if you don't like this perverted MC, This show is not for you. I have said before, this show is about Rudeus Greyrat's life which means you can expect Character Growth steadily in all ages from Infant, Baby, Teenager, Adult.
Sylphy: A quarter elf that got bullied in episode 3. You can see the Sylphy's character growth in 1 episode. When Rudy save her from bullying, Sylphy still scare of him. but later on, she even have courage to ask Rudy to teach her chantless magic and become more cheerful. However she become very depend on Rudy, that's a problem. so there will be another development for her.
Eris: A spoiled girl from a noble family. She is very stubborn, easily get mad, always using muscle to force someone submit to her, even a few teacher can't do anything about her. She is even drop out from school due to her personality. but as story progress, she starting to show progress for better behaviour.
Roxy: Rudeus' Teacher. I think there's not too much character growth for Roxy, because she is already adult around 30s when she started to teach Rudeus. She is also someone that cure Rudy previous life trauma, that's why Rudy respect her not just because she is his teacher. Since Rudeus is her 1st student that is genius ( 5 years old learn Saint Rank Water Magic ), she tends to compare the other student to him. and later she realized it, she started to improve herself on teaching.
Art 10/10:
Gorgeous, Details. I don't think I can see the other anime have same Quality too often.
Sound 10/10:
At first, I don't really like the Opening and Ending because I rare listen to this kind of genre. However, as I keep listening to detail like what instrument they used to fill the song, chord progression, I'm starting to love it. The song feels Calming.
The BGM on each scene is excellent which is fit to the scene.
When Rudy cast intermediate magic, the water sound and breaking wood can hear clearly.
Enjoyment 10/10:
When I watched this show, I can feel it's similar to Ascendance of Bookworm. It feels light, calm for this 1st cour.
Overall 10/10:
Personally, I love this show very much.
Many people give 1 score to this show just because MC is perverted, it's too BIAS. because they only review the main character while ignore It's Art, Sound, Story, Character Growth and the other main character.
