I haven't used postgres for several years, and in that time I've clearly managed to forget it's huge number of annoyances and quirks.
I think that using MySQL, and either mysql-query-browser or Tora has spoiled me a bit, as using Postgres 7.4 (as shipped with debian stable, ubuntu, fedora, etc) is like stepping back 10 years.
Setting up is arcane, admittedly the packagers for the linux distro's are partly to blame for not making it easy - but, crikey, why the heck do I need to create databases before I can even log in, and I have to su to postgres to do so as there is no standard user, and I have to muck about with several configuration files just to bloody access it on localhost
The syntax is archaic and inconsistent and the manuals are lacked worked examples - the mysql docs are much clearer and nicer
MySQL and SQL Server have left me expecting things to JustWork and not require hours of tinkering before being able to run queries.
Yes, I'm sure it gets easier once you've done it for a while, but porting from mysql, which I am familiar with - and never had these troubles with to postgres sucks eggs through a straw
update: attempting to allow a webapplication user multiple permissions to all tables, sequences, etc in a single database doesn't seem to be possible - in MySQL I just grant [list of privs] on dbname.* to user, etc - in postgres I have to list the dozens of tables and associated sequences - this is incredibly tedious. Hateful thing.