I've been using Vimcal for about a month, and it's precisely what I've needed. I operate across multiple client calendars (Google and Microsoft) and always struggled to cobble together a universal calendar (outlook, fantastical, apple calendar) with task management (sunsama, Monday, asana) and with a scheduler (calendly).
Vimcal has absolutely nailed it. The unified calendar is the best I've used and most intuitive (identifying duplicate meetings across accounts is very clever), and the ease of sending along availabilities in a polite and time zone-sensitive manner completely outdoes schedulers like Calendly which are roughly the same price for just the scheduling.
I would love to see more ability for time blocking around tasks, but for being a complete solution for universal calendar and scheduling, Vimcal is best in class. The onboarding process was fantastic and I was up and running quickly.