The UI is Windows XP like. And it's a little complicated to get used to Sticky. There are templates you could use, but they are all templates for notes. You are able to customize templates or change them. But you will find them only local. In Windows, you have to store some registry keys if you want to have your templates back after reinstalling Windows or want to use Sticky on another computer.
The browser extension (Vivaldi) worked... good. Sometimes it worked and sometimes not. It is okay, but not the best experience I had.
For me, the biggest problem was the iOS app. It looks ugly. If you compare it with competitors, Sticky has the worst app in my opinion. Also, it crashed permanently when trying to autofill. I send logs, but support was not able to help. Sometimes it worked again after rebooting my device, but most times I had to reinstall the app. Then it worked for some days till it crashed again.
I think Sticky needs a lot of work...