I mostly agree with the author - Christmas tree is a mess. But I also think the final theme was too minimalistic. I find it incredibly helpful when language keywords like "try", "await", or "new" are highlighted.
We also started with "temporal_tables" C-extension, and also had to switch to NearForm's version written in PL/pgsql to be able to migrate our database to RDS.
Didn't notice any performance drop.
It also much easier to install (just run an SQL-script, no need to restart the DB) and it works everywhere, on all PostgreSQL versions. Great piece of work!
What about "The Wind Rises"?