My first app - TIMER

Hi everyone!
My boyfriend and I developed our first Android app!
It’s a Tea Timer, and we’ve uploaded it to the play store a few days ago:

Since this app is our first one, and we’ve already started working on the next two, we would really appreciate feedback’s!
Any thoughts, comments, suggestions - please share.

Thank you!

I have a question and need your opinion:
We also have a paid version of the timer.
The free version doesn’t have all the features of the paid version - The free one has ads, less preset timers and a smaller collection of cup icons.
We did this because we thought if people liked it, they would buy the full version…
Do you think this is a good idea, or that free versions should have the same features (plus the ads)?