Don't be. Judging from all the apps I tested, making a good calendar must be a really hard problem (but I never built one myself). At least for my use case. I mean, how much money have MS spent on making the new Outlook web thing, and it doesn't even work? I even tried in another computer with a new account, to see if I was doing something wrong. That's how bad my experience was. And Google stuff isn't that much better either. The lock-in is real. The integration with Google Keep is the best thing I can say about it.
I just didn't got the confirmation e-mail. Tried several times the same day. Maybe it was a temporary problem since I tried again and was able to confirm my account.
Regarding the UI, it's just a matter of opinion. I use a lot of apps with bad UI and don't care but a calendar is something really personal and important for me that I just can't deal with something that doesn't feel natural. But my opinion shouldn't matter since I'm just an overly judgmental dev and not the 99% type of regular, business user.