I feel like the first three levels give you a good taste of what WaniKani is all about. It allows you to see whether you even like WaniKani, like the language, or even feel like learning through mnemonic devices even works for you.
Some people can’t learn that way and work best through visual and wrote memorization. I, however, have always worked really well with mnemonics, even as a teenager.
It also allows people to see if they are serious or not. If you think it is too slow at first, but are serious about it, you will push through. If you lose interest that quickly, then you weren’t going to continue, most likely, anyway.
So, I agree with everyone here, that the first three levels being free is pretty good and it is early enough in the levels that when you complete them, you are forced to make a decision about whether to pay and continue or not, especially if you liked it.
I luckily was able to finish level 3 and make that decision around January when they had the Lifetime Membership discount .