weakness and strenghts of PG

Hi

(I have posted this question to pg_advocacy as well, but I want to get
an answer or a discussion from this group as well, separate from the
advocacy group and background)

I am researching an advocation paper on Postgres. Basically I would like
to make a list of the most important strengths and weaknesses of
Postgres compared to a couple of other major databases.

The aim is to have a factual tehcnical background for when advocating
Postgres to potential users.

Specifically I would like to compare:

- PG
- MySql
- Oracle
- MS SQL server
- Firebird

the facts I am looking for is about the core functionality and use
application aspects.

while thae answers I am looking for is for example whether
- one db more or less suited for GIS or warehouse etc
- one db is not well suited for performance operations
- if there are types of operations a database is not good at,
   or conversely, is extremely good at.

I know this is pretty vague, but just focus on what weakenesses and
strengths the different db's has, compared to each other.
And I will try to ask the right questions based on that.

regards

thomas