It's feature complete, and a few thousand people are already using it. It's probably the better choice for most users. But there are still a few issues with the file editor that I want to fix before I officially release it, because I have a lot of corporate users who presumably prefer to have fewer features but more stability.
I'm using it for probably 1.5 years and never had any problems with it. I can highly recommend it. It's really stable and I reported 2 (small, cosmetic) bugs which both got fixed within a few days.
There are annoying show-stopper bugs that the developer refuses to fix, like this one for not being able to set options for null/empty values when importing data from csv ( https://github.com/jakob/Postico/issues/406). Or issues importing CSVs exported by Postico itself, that seems like a pretty basic requirement.
On the other hand, even though DBeaver has an annoying and ugly UX (as any other 90s Java software) and is full of warts (eg not showing a unique key constraint in a postgres table, which was visible in Postico), it somehow feels more substantial.
It's not an empty string bug report. It's not being able to import CSVs with blank values, because postico interprets them as null, and no way to remap the values. Depending on your workflow, this could be a serious hinderance.