This is one of the first isekai I've watched so I guess it remains in a special corner of my heart. 

That time I got Reincarnated as a Slime!

Plot: 7/10, The basics: A man gets hit by a truck and is then reincarnated with a special skill and is also a slime. The main character obtains skills like in a game, however, the world is completely free so there are no quests.

The mc then meets monsters, defeating and befriending them and creates his own country of monsters whilst interacting with other races.
When I first saw this I guess the plot felt original which might not have been the case, but the game-like easy system appealed to me. The first season is the good, the second even better. I've also read the 14 light novels that follow - the plot gets more repetitive and less combat is involved later on with less goals and a not so clear aim. Nevertheless great anime.

Art: 9/10 Beautiful scenery and characters - each episode is like taking a breath of fresh air. Combat is clean and pretty.

Music: 5/10 The opening and ending are decent, they are enjoyable but average. The actual soundtracks contain nothing memorable and are fairly generic.

Characters: 7/10 Mc has a lighthearted nature and his subordinates are also cheerful making most of the scenes appear very fun. The show is quite child-like in this sense. There are no major betrayals in the Mc's inner circle which makes the whole kingdom building seem very easy.

So overall, great show, 7/10, I enjoyed it alot. But it isn't one of those shows that will change your life or leave a lasting impression. If I would compare it to food, I would say it is one of those burgers from a restaurant slightly above Mc Donalds, a higher quality than fast food but nothing really special.