Seems to work faster than before. I had the feeling that HomeKit wanted the exact current status from a device before allowing me to manipulate anything, which meant that slow devices blocked everything. Now it's really responsive.
However, and this may be a dealbreaker for some people, upgrading the architecture required everyone to be upgraded to 16.4, so if you - or invited people - use older devices (not being able to upgrade to 16.4) to control HomeKit I'd NOT upgrade but rather wait and see