I wish they'd just fix search.
I use Google Calendar heavily, averaging ~10 entries per day for the last 5+ years, and then some entries per day all the way back to when it was launched.
I can put information in easily enough, and with a few IFTTT recipes I'm able to treat Google Calendar not just as a schedule for upcoming events, appointments and reminders, but as a historical log of everything I've done. It is a time based database of my life... a diary.
I've automated my diary taking into Google Calendar. The what, where and when of everything ends up in one of 12 calendars (each calendar is effectively a label to categorise a whole group of events that have occurred).
And it's brilliant.
Except for the search.
It's really difficult to get the information back out. If I search for something I know that has happened, or has happened frequently, Google will delightfully tell me that I have matched 200 results, and then show me a list of 9 or 10 of them, with no way to paginate the remainder or search the old ones (it only finds upcoming, not past).
Search is broken on Google Calendar, to the point of being almost totally useless.
Far better to rely on time as a search dimension and jump around dates until one manually finds whatever you were looking for. It's that broken.
Compare to search on a product that has some love: Google Photos. Where now the miraculous occurs, I can search things like "Felicity skiing" and what will return are photos of my wife skiing, and an option to look at all other photos on those days. A simple search and all the results you want, and a single click to expand to view it in the wider context that makes sense.
Google Calendar really needs a decent search. It feels far too much like writing to /dev/null at the moment. Your information went in there, but the chances of you finding it when you wish to reference it are pretty non-existent.