I used Postgres on a project and my main concern with it is that whatever GUIs were available were seriously lacking. Phppgadmin is awful.
If you're really pushing its capabilities then there may be better solutions than MySQL but for bog standard applications and websites there is no alternative as far as I'm concerned.
You should've used pgAdmin [1], it's much better than PhpPgAdmin [1]. I have not used the MySQL GUI (MySQL Workbench [2])that Oracle/Sun/MySQL sells with the Enterprise license but by its feature list I suspect that it provides comparable functionality to pgAdmin (which is FOSS). I would not put any of Php{Pg,My}Admin interfaces in the same category - they're too lacking IMO.
I'll second pgadmin. I finally woke up to the fact that I should start using Postgres a few months ago, and pgadmin made my initial foray into postgres very straight forward
If you're really pushing its capabilities then there may be better solutions than MySQL but for bog standard applications and websites there is no alternative as far as I'm concerned.