There is a tutorial game that you can download that teaches you how to play Minetest in a fun and intuitive way. There are even collectable gems you can try to find in the tutorial.
Parts of the games's graphics and functionality are really bad. Mob mods or default mobs look like a 4 year old drew them. However, the devs seem to be slowly sweeping through these issues. Come back soon if you don't like what you see yet.