I love Calendly and have used it for many years, first in the free version as my business got started and now as a paid user.

The #1 feature I see missing is Minimize Gaps, the ability to show only the available slots that are directly before or after other bookings so that you don’t login in the morning and see four bookings with an empty slot between each as I currently have booked for tomorrow, and not quite enough time to ever make it out for lunch! Of course, one can manage this manually (create a ‘filler’ event on the linked calendar,  and then delete it or move it around as events get booked. But of course one could schedule with clients manually as well if one had the bandwidth!

This feature is so crucial in order to be able to offer broad booking availability, adjust as things get full, and not have to worry that you’ll end up with a day that you’d never schedule for yourself that it prevents me from being able to recommend Calendly more broadly (my hair stylist, for instance, refuses to use it for exactly this reason that he’s afraid he’ll have 3 people book with him in a day, all 2 hours apart or something crazy that will keep him trapped in the salon all day on a slow day). And my business partner, our hiring manager, prefers to use her part of the ‘scheduling software’ budget by using the free version of Calendly for 9 months of the year, and then switching to a paid Acuity subscription for the 3 months of hiring season, so she can open up her availability to show everything she can make work to applicants who are looking at her schedule far enough out but not have her trapped at her desk with dead time between calls. 
 

Calendly, I love your vibe, love your product, please develop this feature to help all of us out here in the trenches maintain some work-life balance!  Here’s the feature description from Acuity: https://help.acuityscheduling.com/hc/en-us/articles/16676902843661-Hiding-your-availability-using-the-look-busy-or-minimize-gaps-settings