I went from 'well it's OK' to 'I quite like this' to 'it's great!' in about 10 minutes.

Creating a new web account loads the tutorial page, but it's a little confusing at first how to add a node. Also, there are quite a few spelling and grammar errors on that page which will make an unfair negative impression. If you clean those up you will get more conversions.

Examples:

  It's my job to keep your complicated brain neat and tidy and remember **things** for a long time!

  Here's how you can **create** a neat Note Garden.

  2. Structure what you have learned and put **it** in order.
  
  I even take care of your knowledge so that you won't forget **it** for the rest of your life!

  (The road to being a great gardener** was **not easy, but we did it!)

Note also in the last example how the bold markdown surrounds the whitespace. I highlighted this manually (and carelessly) but clicking on a word also selects trailing spaces. You should probably strip the whitespace.

On the landing page 'Write Smartly' is correct English, but people rarely use the word this way - although it is technically correct it feels weird, and you don't want to create that feeling on a landing page. 'Write Smart' would be better.

Also, you wrote 'Law students - People who study for a long time that should not be forgotten'. I suggest 'Law students - People who need to study and retain knowledge for a long time.'

These are small language errors, but they would be very quickly noticed by your target audience.

Finally, the desktop sign-in with Google seems not to work - it opens a blank window and then closes again. Maybe it is just from server load right now.

Anyway I like it a lot and will consider using it regularly. I am more of a pencil-and-paper note person but this is one of the nicest digital notebooks I've found.