Honestly, when the anime was showing what they advertised in the synopsis, it was great. When it was about actual adventuring/traveling with a slime companion, I was hooked. But the second half stops the pacing dead in its tracks to solve a great mystery, and I dreaded clicking on the next episode every time. I came for cute slime interactions and adventure, but that's not what the main course was. If you were here because you like slime creatures, prepare to be disappointed.
Visuals: Great. I loved the way the anime looked, they animated Sora very well. The colors that were used matched the flavor of the show - lighthearted, cheerful, and laid back. No complaints here. Also, the sound was fine. Not going to make a separate paragraph for nothing.
Characters: Whatever. Ivy can do no wrong, which gets old fast when it's the same characters praising her. If she continued traveling to different towns and meeting different people, I would have certainly overlooked it. But it just becomes the same group constantly impressed by her previous-life's knowledge and it's just tiring.
I enjoyed watching Sora evolve physically and mentally more than anyone else in the anime. The little interactions Ivy has with him moved my heart, especially when I got to realize that Sora is becoming more mentally capable of communication. But in the second half, he's basically locked away in a bag with minimal screen time.
The last episode was very good, compared to the arc that it closes. And I don't mean that in a "haha it's good because the anime is over xd" kind of way. I genuinely enjoyed the final episode. I mention this because if you can push through the arc that it wraps up, you're perseverance won't be <i>completely</i> unrewarded. Even with this last note, I still cannot recommend this anime. Sorry!
Final score: 4. That's how big of a slog it becomes.